HELP! I can't save anything after a loss...

Hello,

This is my problem, i hope someone could help and emal me ASAP

i have a dell home edition laptop. my brother was working on it last night and when he tried to turn it off normally it wouldn't shut down so he just pressed the off button for 3-4 seconds. the next morning i turned the computer on and it was on the users screen a screen popped up saying it can't recognize previous user files. Now i believe im on a guest account and i can't save ANYTHING on here cuz if i save it and i restart its gone because it can't recognize it. i was wondering what i could do to fix it since this had never happened to me before where im not able to save anything and redownload files.

thank you feel free to email me