packard bell external hard drive

hey,i bought a packard bell store and save external hard drive last month,somtimes windows will recognise it,but most of the time it wont.im after trying everything.its formatted,partioned,it has the proper drivers,the drive letter is assigned properly,i got registry mechanic and cleared everything.when windows does recognise it,in device manager,everthing seems fine.the disc is healthy and working fine.then all of a sudden,it will turn off and wont come back on.dear god,someone out there must have an answer,before i turn this annoying hdd into a dartbord.please please please.thanks