My macbook wont recognize 500GB WD hard drive

I have a 500 GB WD hard drive and till yesterday it worked fine but this morning neither my macbook pro or mac mini recognizes it...! it would show up in Disk utility or system profiler but it wont show up on my desktop. I used both firewire and USB port neither would work...! I tried different ports in my laptop again non would work...! anybody knows whats going on?

If it shows up in Disk Utility, but won't mount, chances are the filesystem is damaged in some way. Have you tried running First Aid?

no wat is first aid?

In Disk Utility, click on your HD and click the button "Verify Disk" under the First Aid tab. What results do you get?

oh k thank you. I chose my hard drive on the first aid tab, but the "verify Disk" option is disabled