Help! Windows not working....

My guess would be he removed the video drivers and so Windows reverted to the "classic" look for the interface because the "normal" one for Vista and later uses DirectX, so needs video drivers installed.

He'll need to figure out if he has an Intel, AMD or nVidia video chip and then get the appropriate driver from their website. Then the next time he feels like doing a little mass deleting, tell him to google each item first to figure out what it is before he goes and deletes it.

If you do try doing a windows repair.

http://www.dummies.com/how-to/content/how-to-use-a-system-repair-disc-to-restore-windows.html

Try repair first.

I really don't understand when you told that your computer is acting like its running XP. What is it specifically graphics, speed. If it's about speed, then you can try cleaning the temporary files, run disk cleaner, clear error log files, etc. If it's graphics, then I presume that your brother might have uninstalled the Visual Studio C++ redistributable packages. You just have to re-install the graphics drivers.

There can be several solution for these::
1. Check the appearance setting. Re apply the standard windows 7 theme
2. Re-install the video drivers:
a. Goto device manager and right click on display driver and uninstall the driver. Then click on scan for hardware changes in right click option
b. If not work , reinstall from driver cd
3. Repair the windows with windows dvd , just repair, no need to format it, this point is the last option...

I agree it sounds like you need a video driver. However I hope this makes you realize the need for backing up your computer. When you've gotten your system back like you want it, I urge you to get yourself an external hard drive and a good 3rd party backup program. You can set it up to do everything automagically at the time and frequency of your choice. 1 TB external hard drives are about $60 these days and a really good FREE backup program is the Easeus Todo Backup Free. That can save you a lot of time and frustration the next time something like this happens. Sooner or later it happens to all computers for one reason or another.

Good luck.