I have a dell 530 pc desktop which it want restore to factory settings. i have tryed every thing i have found online. when i restart my pc it ask me which operating system do i want to start. what do i need to do

before u enter the post look on the screen wich button u need to press f4 or f9 for recovery

Hello,
First, if the computer has the restore partition, you should see a blue bar at the top of the screen immediately following completion of POST. After two seconds you should see a message about loading the descriptor for PBR2. If you don't see these things after you start or restart the computer, the restore function is not operational. If you do see them you need to restart the computer, press CTRL and F11 toward the end of POST, and release both keys simultaneously before you see the message about the descriptor for PBR2. If you are successful you will get a screen that has an option to restore the computer to factory configuration.
If you don't see the blue bar, try using Disk Management to see how many partitions you can find. If the partition exists, you should find three. First, a utility partition formatted in FAT-16 about 32 MB in size. Second should be the NTFS partition used for the C drive; this one will be the largest partition on the drive. Third should be a FAT-32 partition of two to three Gigabytes in size. This last is the restore partition. If you wish you can try to fix it, but you will need to study Dan Goodell's page found here: Inside the Dell PC Restore Partition.
If you don't have the restore partition and can't fix it, the only thing you can do is find the CDs that should have been shipped with the computer and restore the system manually. If you don't have the Dell Windows Reinstallation CD, you can ask for one here: Dell Replacement Disks. If you don't live in the U.S. you will need to contact Dell Tech Support for your region and request the CDs.
Hope this helps!

Turn off the computer, wait a few seconds and then turn it back on. As the computer starts up, press the F8 key until you see the "Advanced Boot Options" menu appear.

Select the "Repair Your Computer" option and press the "Enter" key.

Click the "Next" button, log in with your Administrator username and password and click the "Dell Factory Image Restore" option.

Click "Yes, reformat hard drive and restore system software to factory condition" and click the "Next" button.

Click the "Finish" button. The computer will restart in its original factory condition.k

Note: Kindly back up all necessary documents before starting restoration as it would be deleted.

Dell system includes a restore utility called 'Dell Symantec System Restore' to reset or restore your Dell system to factory setting. This utility is convenient because you're not forced to use the Windows startup CD to restore your computer.

Step 1: First backup all your important data and restart your computer.
Step 2: Press 'F8' if you are using Win7/Vista or 'Ctrl + F11' if you has Win Xp. 'Advanced Boot Option' menu options will be opened.
Step 3: Choose 'Repair your computer' from the 'Advanced Boot Options' from the menu and press 'Enter'.
Step 4: Select language setting and press 'Enter'. Now Login window will be appeared.
Step 5: Now login as administrator to continue the factory reset process.
Step 6: Click 'Dell Factory Image Restore' followed by the 'Next' button.
Step 7: Choose the check box marked 'Yes, reformat disk drive and recover system software to manufacturer condition'. Once the check box is chosen, simply select the 'Next' button and your Dell computer/laptop is renewed to factory setting.
Step 8: Press 'Finish' once it has been done. ...

This process will erase all your previous changes that have been made to the Dell computer and reset the configuration settings to factory setting.

Feel free to get technical assistance anytime at http://www.vtechsquad.com/dell-support/

i found this solution elsewhere. basically you want to try and do a factory restore , if this is no help do a google search on "Dell Dimension 5100 factory restore"
"OK try this, when dell screen comes up on keyboard hit CTRL+ F11 twice only then you will see Dell pc restore by Symantec.Hit on restore and hit on i agree and select the option Restore the pc to Dell factory settings and then it will restore the pc "

1. While most Dell desktops respond well to "System Restore," which restores the Windows operating system, occasionally a computer may need to be restored to factory settings. This is usually done as a last resort and is usually due to viruses that can't be removed. While you should try "System Restore" on your Dell first, resetting the desktop to factory settings is an option. This is done through a PC restore by Symantec. Be aware that not all Dell desktops have this ability, and before proceeding with this option, you should call Dell tech support
   
   

2. Make copies of all things on your PC you want to save, such as photos, documents and other installed programs. Resetting your PC to factory settings will erase all data on the hard drive. It will erase anything that you installed on your computer after you received it.
   

3. Restart your computer.
   

4. As the computer is turning on, you will see a blue bar that says "Dell.com" across the top of your monitor. At this time, press the Ctrl and F11 keys simultaneously. If you wait too long, you will miss the opportunity to do this and will have to restart your computer again.
   

5. Click the "Restore" option when the next screen appears.
   

6. Click "Confirm." The PC will begin its resetting process. This process takes approximately 10 minutes.
   

7. Click "Finish" when the process is complete. Allow the PC to restart itself. Do not restart it yourself since it needs to run through its boot program.
   

8. Click "Yes" to allow the computer to restart. When it does, it will be at original settings, and you will see the "End User License Agreement" screen. Click "Next." The System Restore screen will appear, and the computer will do another restart.
   

9. Once it does another restart, click "OK." You have now reset your Dell desktop to factory settings.
   

If I could be of further assistance, let me know. If this helps or solves the issue, please rate it and give a testimonial for my response.

Thanks, Joe

I’m happy to assist further over the phone at https://www.6ya.com/expert/joe_8b8c2cd6ce148309

goto :
Start
control panel
power options
change your power options..

or .. press f2 or delete key or whatever key it is to go to bios (system setting) and find where it says restore factory settings. select yes.

call dell and get the factory program discs as well as factory restore discs...They'll make you happy!!

CTRL F11 should launch your restore partition for you.

dont restore to factory settings, you have a virus. try avast antivirus freeware and see if that cleans it up...