Read the most common issue at https://www.servethehome.com/fix-746gb-3tb-hard-drive-issue/
I have a 3TB internal HDD (Western Digital Caviar Green 3 TB SATA III 64 MB Cache Bare/OEM Desktop Hard Drive - WD30EZRX) that I had partitioned into two 1.5 TB partitions, E and F. I needed to merge the two partitions (E, F) back into one (E). I removed all files from the F partition and deleted the volume and then deleted the partition. I then attempted to extend E to reclaim the unallocated space freed up by deleting F, but I don't see the 1.5 TB of unallocated space in Disk Management. What am I doing wrong?