External hard drive is not recognized after I abruptly removed while time machine was erasing files?

So what is your goal here? Recovering the files, or recovering the drive for Time Machine?

If the former, contact a data recovery service and see if they can recover some of the files that might still remain after the interrupted reformat and the yanked cable. Some recovery tools on the ‘net might work here, or might not given the particular sequence. I’m not familiar with Windows file recovery tools for what is likely an NTFS volume, though.

If the latter, reformat the device as GUID/GOT partitioned and HFS+.

Drive Preparation - El Capitan or Later

1. Open Disk Utility in the Utilities' folder.
2. After Disk Utility loads select the drive (out-dented entry with the mfgr.'s ID and size) from the side list. 
3. Click on the Erase button in the Disk Utility toolbar. A panel should drop down.
4. In the drop down panel set the partition scheme to GUID. Set the Format type to APFS (SSDs only) or Mac OS Extended (Journaled.)
5. Click on the Apply button and click on the Done button when it is activated.
6. Quit Disk Utility.

Unplugging a drive without unmounting it first is a sure way to corrupt it. I would reconnect it to Windows since that's the system you're familiar with and try using the utilities there to read it and hopefully save the data.

Pulling a drive during a write operation is asking for trouble. The worst outcome is the drive is damaged physically and will no longer be usable. If the drive is not recognized, then you need to try connecting it to another computer to see if it is still functional. If it is still working, then retry connecting it to your Mac and try using another cable.

If the drive no longer appears to work, then it is likely the worst has happened. Thus far, this discussion focuses on mechanical drives.

If the drive in question is an SSD and does not work on another computer, then it has been damaged. SSDs are far more susceptible to damage when yanked from a computer during a write operation. I made this same mistake accidentally thinking the SSD wasn't turned on. I've tried everything to get it working but without success. It seems dead as a door nail.