cleaning up a user accounts mess

Hi, I got a second-hand PC with windows 7. I deleted the previous owner's accounts and created new ones called Owner (regular) and Owner-admin (admin access). Since then everything is messed up...

The previous owner account still had files in /users/[account name]/ after I deleted the account. I deleted those and they were mostly gone, but some are protected or are recreated on reboot. Even though I always log in as Owner, downloaded files often en up in the previous owner's "My documents/downloads". When I try to copy them into my new "My documents/downloads", I don't have write permission. I can't write into my own user account directories...? I thought I'd recreate the previous owner's account and try to undo it from the inside out, but ended up with a ‘Owner.Carl-VAIO.Carl-VAIO' as well as a ‘Owner.Carl-VAIO' account. I tried to install Thunderbird, but it is so confused about what is what that it won't install. I can't blame it.

After it was already too late I discovered that my computer thinks it is part of a workgroup. I tried to reset this (it's a standalone), but I couldn't - the button remained greyed out no matter what. Not sure if that has anything to do with the problem.

What can I do, other than re-install the OS with an installation CD I don't have?

Thanks...

Welcome to Windows Seven Forums.

Providing you have a genuine product key that came with the computer (there should be one on the COA sticker) you can download a Windows 7 ISO the same as your current version of Windows and use it to carry out a clean install, as explained in this tutorial.

Clean Reinstall - Factory OEM Windows 7

In view of the current state of your computer I would certainly advocate a fresh start with a clean install.

I didn't know that! That should work. I'll give it a go, thanks!