If you accidently delete your stuff, often it can be recovered with free software that will restore those files. Best to install that software before you lose anything if your stuff is on C drive (which it shouldn't be - use a separate drive) because you can't be writing new stuff on the drive or it will overwrite the space occupied by your 'deleted' files - which are not in fact deleted at all - deleting merely tells the computer that the space is now free and can be used again.
If you are backing up on a data DVD, use the gold type, which don't deteriorate anywhere near as quickly as standard cheapo DVD-+Rs.
If a hard drive fails, don't bin it. It is often the circuitry that has failed, and you can look on eBay for a used but working drive of EXACTLY the same model and swap the circuit boards - they simply unscrew and unclip. This can get the drive working again so that you can transfer your stuff to a brand new drive.
Also, if your stuff is on C and that drive fails to boot, don't panic and start re-installing Windows if your stuff is important. Simply remove the drive from that machine and hook it up to a working machine as a second or slave drive.
The working machine will very often recognise that there is a problem with the file system on that second drive and will repair it for you. Then simply return it to its own tower and it should boot (I have done this many times for people). Then you can transfer your work to a USB drive or whatever.
Losing your stuff is not always as bad as it seems - main thing is not to panic by overwriting the space where those files are stored.