Web History

I have suspicions of what someone has been doing on my computer, possibly getting into my online accounts and email.

Is there a way to retrieve the websites visited history for longer than what Internet Explorer offers? (I think it's up to three weeks.)

If the person has deleted the history, is there a way for me to get it back?

Lastly, what free monitoring program works well for me tracking this stuff in the future? I want to protect my files, etc., but I need to find out if those web pages were accessed before I can make the changes.

Thanks a lot for your help!