Cannot Partition or Create Volume in Disk Utility

I have a 3 TB disk that I used for video files that I now want to use for backup. So I wanted to erase and partition the drive to wipe it clean. So after going into Disk Utility and "trying" to erase and partition the drive, it now only shows the drive and no volumes. The problem is everything is pretty much greyed out and I cannot create or partition volumes. I don't know what I did wrong or what to do to fix it. I tried verifying and repairing the disc but that didn't do anything. The only buttons available are Verify, Info and Burn. What do I do to use the drive again? Please help, thank you