Is there any way to get in to 7 without any account? There's a student who have forgotten his password, and the administrators account is deleted. Please help he has a lot of work on the computer and he dosen't want us to reinstall the os.

You can either remove the hard disk and attach it to a working system or use a live CD\DVD\USB stick, e.g. Knoppix http://knoppix.net/, to access the disk and copy the files to an external drive before reinstalling the system - assuming the hard disk is good.