My external hard drive has stopped working 

My Iomega external hard drive has stopped working and is making a intermittentwhirring noise & is struggling to spool. I have checked all the leads. All the power rights are functioning correctly. For the last few days My external Hard drive has been repeatedly going on and then coming off on my computer start menu. What do I do? My life is on there. I have had this for about a year. It's a 1TB machine.Please advise