fatal error LNK1120: 1 unresolved externals

This error occurs when the linker is unable to resolve a reference to an external symbol or function that is used in the code. This means that the linker is unable to find the definition of the symbol or function that is needed to link the program.

To fix this error, you need to ensure that all the necessary libraries and object files are included in the linking process. This can be done by checking the project settings and ensuring that all required files are added to the project.

You should also check that the function or symbol that is causing the error is properly defined and declared in the code. If it is not properly defined or declared, the linker will not be able to find it and you will get this error.

Finally, you can try rebuilding the entire project to ensure that all the necessary files are properly linked and that there are no other errors in the code.