huge problems with hdd

hi I have been running my games from hard drive for a while now but the other day I tried loading up hdadvance the disc loaded up all right but took a long time to detect my hdd as it does normally (its formated by hdadvance) after nearly a minute its says cannot find hdd but as hdadvance starts up whenever my ps2 v7 try's to access it it makes a high pitched ringing noise as soon as i unplug it it stops.How can I fix this