1. Open bitcoin-qt
2. Open debug console, help->about->console
3. type in "dumpwallet <filename>"
4. if above command is invalid try with "dumpprivkey "
well you have a treasure there
I think he can't be able to go on the debug console while he still getting this "error: prune" when using bitcoin core.
What he needs to do is to disable the prune mode just to get rid of the error before he can be able to go to the debug console.
@BitCoinSeo
Look for bitcoin.conf and edit with notepad and then find the "prune=" remove that thing and restart the core.
After that, do what BITDV suggests.