My daughter played with the buttons on the E173FP monitor and now the screen is too dark to see the menu to reset/adjust the color.

SOURCE: dell m782 Brightness control???

Brightness is adjusted by using the 2 buttons on the left side of the front.

See instructions here:
http://support.dell.com/support/edocs/monitors/m782/En/controls.htm

SOURCE: Dell E173FP

I have a Dell E171FPB monitor that had the same problem with the Main Menu coming up and I thought I would tell you what I did to fix the problem.

1. I shut down the PC.
2. I removed the power cable and video cable from the back of the monitor.
3. I removed the four screws that hold the stand for the monitor and slid the stand off.
4. I then removed the 5 screws that hold the back cover on the monitor.
5. I took two flat blade screw drivers and carefully removed the back cover.

At the bottom of the monitor case, there is a small circuit board the holds the 6 switches for controlling the display.

6. I located the button that calls up the Main Menu. It is the second switch from the left as you are looking at the monitor from the rear.
7. I used a small solder iron and heated up the four prongs in sequence while holding the switch with a pair of needle nose pliers. I had to rotate this process from one prong to the other while all the time applying slight pulling pressure on the switch pulling it away from the circuit board.
8. Once the switch was removed, I put the cover back on and tightened up the five screws.
9. Then I slid the base back in the slot it came from and tightened the four screws.
10. I connected the video and power cable and turned on the PC.

With the switch removed the Main Menu never popped up again and I am so very happy.

SOURCE: Dell E173FP´s main menu keeps flashing up

The trouble is probably due to failure of one or more of the switches on the circuit board that the front panel buttons operate. Sometimes they begin to act up from age and use, and sometimes they suffer from the "Windex syndrome." That's when spray cleaner has been used to clean the face of the picture tube, and some of it runs down and gets into the switches and associated parts. The best cure is to replace the switches and check the parts around them for damage or changed values. A number of vendors online offer replacement switches ("tactile switches" is what that type is called). Changing them requires skill in soldering, but it's not an impossible task. If you don't feel up to trying it yourself, you could check at a TV service shop to see what they would charge. Or, given today's low prices on LCD monitors, it might be a good time to consider replacing the CRT version you have now.

SOURCE: Screen Appears Blank

This is what you're looking for.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&Item=220476282873

SOURCE: I have a Dell E173FP

I have the same problem. I have spent alot of time diagnosing it. It is the button assembly malfunctioning.. The button assembly needs to be replaced but I have looked everywhere for a replacement part but none cane be found because none are sold. It sucks. If you take the case off you can see and remove the button assembly fairly easily. I think if your are good at soldering, the best thing (and only thing you can do) is to purchase individual replacement buttons, remove the old buttons and solder new ones onto the board. I am really bad at soldering so i will never do it. I hope this helps.