I HAVE A DELL INSPIRON 1721 WITH WINDOWS VISTA. IT WILL TURN ON AND LOAD UP BUT AFTER THAT THE SCREEN TURNS BLUE AND SAYS A BUNCH OF WRITING

To restore a Dell Inspiron computer with a Windows 7 or Windows Vista operating system to factory settings, users simply need to press the F8 key when the Delllogo appears. Then, they should select the "Repair your Computer" option from the advanced boot menu, which may require a password.

Do you mean the LCD screen with the lid?
If so you undo the hinges and disconnect the video and power leads to the inverter.
This WEB site shows how to remove the screen/hinges.
Replacing Display hinges
http://www.laptopparts101.com/display-screen-hinges/

You maybe have clean up your Dell inspiron 1721 and maybe your unit or processor were overheated during burning. First, clean up by removing a dust from the unit by blowing air. Sometimes even by mouth with several times enough.
Second maybe necessary to clean up your operating system by removing unnecessary programs from autoloading when a computer starts. This will increase volume of computer memory. You can use program CCleaner free version.

<P style="MARGIN: 0cm -6.4pt 0pt 0cm" class=MsoBodyText2>You can download the drivers from Dell WEB site, the support download page. Make sure you select your model desktop or laptop, better still, type in the Service Tag number, it is printed on the label on the bottom of the laptop and on the back or sides of a desktop. (If the Service Tag label is missing then go into the BIOS setting and on one of the BIOS pages, the Service Tag number will be displayed). This will open the page where the specific drivers for your model computer are located. Also make sure you select the Windows XP or Vista version of the drivers for your Windows operating system. Click on this link to download the drivers: - </P><P style="MARGIN: 0cm -25.7pt 0pt 0cm" class=MsoNormal><SPAN style="FONT-FAMILY: Arial; FONT-SIZE: 10pt"><A href="http://support.dell.com/support/downloads/index.aspx?c=us&amp;l=en&amp;s=gen" target=_blank>http://support.dell.com/support/downloads/index.aspx?c=us&amp;l=en&amp;s=gen</A><?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></SPAN></P>

ok, theres a small issue with the raid controller. You have to install a 3rd party raid driver (its on the dell cd) to continue, OR, you can set that BIOS's hard drive controls to ATA or LEGACY (legacy would likely work best, but youd have no 'raid' functions, but who sets up raid drives on a notebook?). Your last option is use the dell discs to restore, and inssert the windws disc when prompted

Use external USB CD/DVD Drive to run your Windows Vista Operating System to Restore Disk.
Maybe your Built-in CD/DVD cannot read or access your OS.

If you don't have this device, you try another Windows Vista OS Disc.
Good luck!

Power off.
When you power back on hit F8 and from menu select safe mode.
Let windows come up then shut down and try to power back on.

You need to reinstall the audio driver, if you need to, you can download the drivers from Dell WEB site, the support download page. Make sure you select your model laptop, better still, type in the Service Tag number, it is printed on the label on the bottom of the laptop. This will open the page where the specific drivers for your model laptop are located. Also make sure you select the Windows XP or Vista version of the driver for your Windows operating system. Click on this link :- http://support.dell.com/support/downloads/index.aspx?c=us&l=en&s=gen

Seem like you have the bright very high, try dimming a little bit.

checklist:
1. sound driver 2. microphone settings in volume control applet 3. tap test (tap the area around the microphone and see if eg Sound Recorder picks it up) 4. external microphone
If you get to step 4 before you get anything then your problem is one of missing or damaged microphone.