Easiest way to solve it if it just happened is use system restore.
Something! covers a lot of ground.
To hide a folder you have to highlight it, right click it and go to properties then click on hidden.
However if you arent on don't show hidden folders they would still show but possibbly be faint in colour comapred to the others around it.
If folders have disappeared completely (not in the recycle bin are they?) and your on windows 7... Go comupter local drive c: Organize/folder and search options.....click on Veiw and make sure show hidden files and folders is clicked.
Anything you have folder hidden when you were messsing about should reappear even if faint....you can then unhide them
