Re your lost files - I think we've all been there and it's a lesson hard learned to back up your files on a regular basis. At least if you're going new, the new computers will handle flash drives and they're so handy and convenient for backing up massive amounts of data (I even have data duplicated on a couple of flash drives just in case one of the flash drives develops problems).
Re laptop vs desktop - I've got both. I've got a laptop that I bought back in the '80's and it still works ('Impulse' brand, fyi). Generally, I think the desktop will live a little longer than a laptop but it really boils down to personal preference and intended use - I suspect if you're not doing stuff that requires lots of power by way of ramped up video cards, heavy process speeds, etc., that a laptop will be fine. Both my desktop and current laptop are HPs.