Hi, a_subscriber and Kadaitcha Man.
I guess that you are stuck in an almost unresolvable error loop.
Synaptic and apt, both are merely frontends. In the end, on the lower level, they all make use of
dpkg in order to install, update, remove software packages.
The moment that the executable file
dpkg (/usr/bin/dpkg) had been deleted, the worker
dpkg was gone.
In this situation I would not hope that any Synaptic or apt operation will succeed, which depends on
dpkg.
In case a_subscriber's statement was right
In my host I accidentally delete file dpkg.
then at this point in time it might still have been possible to use a matching live system e.g. and to copy the /usr/bin/dpkg executable from the live system to the installed system (and hope the copied dpkg has got the right version. So the live system should have been the same version as the installed one: LM 20.2.)
Now, I suspect, the best chance may be
+ booting from the live system LM 20.2
+ creating a chroot environment
+ installing dpkg on the installed system from the chroot environment
(No, please, do not ask me to explain the details. I would have to look them up myself.
I simply do not screw up my systems frequently enough in order to know such steps by heart.
)
Hope this puts you on the right track at least.
Regards,
Karl