Recognizing external HD

i had my HD fail this week, i replaced it and installed OS X. I have my time machine back-ups on an external drive that wont show up on the desktop. I have gone into disk utility, and attempted to mount, and was denied and suggested to use first aid. After verifying the drive and getting the "volume ok" it still wont mount. I notice that it also is listed as a "read only" How will i change this to "read and write" and get this to work?

Can you see the drive at all in the Finder? In other words, does it show up in the Finder side bar? If it does do this: Right click (command click) on the drive, select "Get Info". At the bottom of the dialog box you'll see the permissions assigned to the drive. Click on the small lock and enter your Admin password. The lock should open. Now change the permissions on the drive to Read and Write.

Try remounting the drive.

No, it doesn't show up in finder at all. It wont let me repair the disk even after verification.

If Disk Utility refuses to repair the drive after verifying it, the drive may be having problems. Do you have another Mac you can try attaching the drive to?

i have a hard time believing both drives crap out on me in the same week. I do not currently have access to another mac.

after a few restarts the computer recognized the HD, weird but im happy now!