fix computer errors

what is wrong with my friend computer she has window xp and all this stuff not working for her “sys restore,defrag,disc clean up,checking disc for errors” and when she try to go on her social networks sites it wont load saying page not found and she tried sys restore and it did nothing, she said she cant go back to no dates what is wrong with her computer??
i know this not in the right place so dont start please more people come here so this is where i put it at