We cannot fix this for you: we do not have access to your code, and you need this to fix it.
LNK2001 and LNK1120 are both concerned with undefined symbols: your code is referring to a symbol which can't be found in the object files or libraries you are linking together.
Linker Tools Error LNK2001 | Microsoft Docs
Linker tools error LNK1120 | Microsoft Docs
The error messages themselves contain the name of the symbol - and we can't even see that, much less the code that tries to reference them, or the list of files that you are trying to link together.
So start with the error message, look at your code, and try to work out where it should be declared.
Sorry, but we can't do any of that for you!