Note: it is possible that corruption (e.g. hardware error) caused the inability to remove the drive safely, not the other way around. Does the drive click or in any way sound different than before? Can you check its SMART status? (in Linux
smartctl -x /dev/... as root). If you do not want to hire professionals and you want to try to recover the data by yourself, the recommended step is to assume the drive is going to die and to copy the whole drive to a healthy device (or to a regular file) with GNU ddrescue or similar program. Taking the drive out of the enclosure and (cont'd)