Partition won't mount
I pulled the usb power port from my time machine backup disk without ejecting it first, and since then my 2nd partition won't mount in 10.11. It did show in 10.15 after I did a time machine restore, but when I restarted in 10.11 it is gone, though it shows in Disk Utility. I have 10.11 on the first partition and 10.15 on the second.
I saw a post yesterday that referred to some Unix commands that fixed the problem, but I can't find it this morning. In diskutil list it shows as the following:
4: 7C3457EF-0000-11AA-AA11-00306543ECAC 249.1 GB disk0s4
Thank you in advance for your help!
Mike
Mac mini 2018 or later