What operating system are you using? What backup software are you using? Are you using the default settings for that software?
You see, there are many backup programs out there - I entered "backup software" into Google and got about 183,000,000 hits. Some allow a user to backup an entire system, including installed programs (commonly referred to as a "disk image"). Others merely allow certain selected files to be backed up. Some do both.
IMHO, at the very least, these are the files you should backup: Documents, pictures, videos, music, downloaded program installation files, emails and browser favorites. Your backup software MUST allow you to verify the integrity of a backup after it's created so you can be assured that the backup will work when needed.
When I back up say onto a disk, does it automatically back up all my documents and programmes as well or just my documents and pictures etc. I have downloaded a lot of programmes, i.e. c cleaner and open office and I would want to back them up as well, is that possible as I do not want to spend time downloading all the programmes again from the internet.
also is there a complete way to back up my system without losing my programmes and files, so if my PC crashes I can just load all my programmes back onto my system again, I understand I cannot back up the windows files because I have a recovery disk for that.