|If none of the above suggestions work... a very lo----ng shot...|
If possible remove the drive from its housing; wrap in paper towel; place in plastic bag (sandwich bag type is ideal). Place in a freezer for about half an hour or so. Remove from freezer; open plastic bag and loosen paper towel around the drive - but leave in contact with the drive. Let it sit for about 5-10mins or so; not too long... Then re-instal into its housing and see if it will spin up and allow access when connected to a computer?
You can also try the above with the drive still in its housing; but ideally remove the drive etc. if possible.
The reason for letting it sit for a few minutes still wrapped in paper towel after removal from the freezer, is to let it warm up "slightly'; and thus allow any condensation on the surface various to be absorbed by the paper towel.
If this routine works at all you may be able to recover data in "bursts'; as it may only work for limited time period before you will have to return it to the freezer and repeat the process as needs-be. It will inevitably fail to work at some stage... Do not try to recover/re-use the drive afterwards.
It is I emphasise a "very long shot"; one that is occasionally successful in circumstances where a drive simply fails to spin up... Usually such drives have started to give audible signals (screeching, scratching, clicking etc) that they are starting to fail... If all else fails with earlier suggestion then no harm to try this approach?
Incidentally I have had one Seagate external drive that failed within its housing - and was OK when installed in another... It's still OK too and that is at least three years since.