Version "5.4.0.60.63' for "linux-generic' was not found

[Jan Gorecki]

Dear kernel team,
Using Ubuntu 20.04, I made an upgrade linux-generic:amd64 from
5.4.0.60.63 to 5.4.0.62.65.
After upgrading, the touchpad stopped working.
I wanted to revert to the old version but apt cannot find it anymore
giving following error

apt install linux-generic=5.4.0.60.63
...
E: Version "5.4.0.60.63' for "linux-generic' was not found

Why is it so that 5.4.0.60.63 cannot be found? How can I resolve the
problem and revert to this working version?

Thank you,
Jan Gorecki