There is a strong possibility that your friend has caused you to lose your data that is on your computer. When restoring through system restore and the program is interrupted it sometimes causes a failure that is beyound anything other than a complete reformat and reinstallation of the operating system.

With the missing dll error code you might be able to get it to start back if you can replace the missing dll. The problem is that you need to be into the system in order to do so....This means that you will have to remove the harddrive from your computer and slave it to another computer in order to replace the missing dll. And then even this may not work.

another option is to try to do a sytem repair(repair option 2)in which you have to use an original installation disc to reinstall windows over itself...this normally will not hurt your personal data but since you were performing a system restore your personal data may be locked and unrecoverable.

to do the second repair option:
Boot to the CD and when prompted to hit any key do so. This will then start the set up proccess. follow the prompts....when it asks that if you want to repair an existing operating sytem (repair option 1) or continue with set up...choose to continue with set up. Set up will ask to install on a certain partition or repair the system on the partition...choose this repair option( repair option 2) and just follow the prompts. You may have to reactivate so have your license code available. You will need to re update the complete computer but with SP3 now available it shouldn't be that bad!