Post 12 says nothing.
There is an evident communication problem.
Of course it is very possible that I am a little bit tough, but surely you are not putting a minimum amount of diligence in attempting to detail what you tried, what you obtained as result, etc..
It is extremely difficult (and tiring ) to have to guess things:
since the problem (in the sense of what I am trying to understand from your one-liners) is WHAT the actual problem is, this doesn't help much.
For all I know the particular machine (or version of OS or its settings/environment, *whatever*) may behave very differently from any other one.
From what I know (very little, rest assured) about that mechanism:
1) Network credentials are stored in the vault as "Windows credentials"
2) the Nirsoft tool normally can access Network credentials from an offline vault.
You could try other tools, but I am unaware of other free ones, passcape has a tool:
but cannot say if the trial/demo is enough to check that.
As a side-side note - and if I may - in a domain/professional environment/whatever it is unusual that you do not have a copy of those credentials (hardcopy on paper) .
Anyway, since the offline method isn't working, did you manage to (slowly) boot the affected system ?