Old HHD not being recognised by the laptop it came from

Grumpysally

I've replaced the HDD in my laptop with an SSD. In frugal fashion, I put the HDD in a caddy to use as external storage. I've done this before when sending old laptops for recycling. However, for some reason, the Acer Aspire I took it from does not recognise it. It shows in settings in Devices and Printers, but not as a drive in Windows Explorer.
I plugged it in to my partners laptop and it is recognised and writable. I formatted it so it shouldn't have anything on it that makes the Acer think it is the same as the C drive.
Does anyone have any suggestions?
I have turned the laptop off and on again, and restarted it.
Everything is working fine with the new SSD, (though speed not as much improved as I expected)
Thanks  

Neil_Jones

Go into Computer Management -> Disk Management and assign it a drive letter.

Sometimes Windows gets confused and doesn't assign a drive letter if it thinks the drive is similar to another device.

Grumpysally

Neil_Jones said:

Go into Computer Management -> Disk Management and assign it a drive letter.

Sometimes Windows gets confused and doesn't assign a drive letter if it thinks the drive is similar to another device.

Thanks. I tried that but the options were greyed out. So I put it in OH's laptop and christened it Drive Z.
Plugged it back into mine but no difference. It still showed as drive offline There was a message next to the drive diagram(?) saying something like the drive was offline because it shared an identity. I realised that it was clickable and was able to change it to online. Eureka. 
Thank you. I was tearing my hair out over it, mainly because I didn't want to be beaten by technology 😁