First, if your BIOS supports it, enable SMART monitoring for your HDDs. For reasons I may never fathom, most motherboards come with this option disabled by default.
Then, a cheap and easy thing to do, is replace the IDE ribbon cable. Should cost less than $5, and it's about a 30 second job with virtually no possibility of screwing things up.
If that doesn't help, then your drive is probably going bad, and I hope you backed things up recently because it could just flat out stop working at all any time.
when I start my desktop up it tells me that it can not find the hard drive, or it will start loading or load windows and then it will stop and say hard drive can not be found. I've checked the connections and everything seems to be pluged in. how can I find out what's wrong or if some wire might have gotten damaged or broken?