After resolving the immediate issue (reactivating server credentials), verifying system functionality ensures the solution works as intended and the user can now access the shared drive. This step is a part of the CompTIA troubleshooting methodology:
Identify the problem.
Establish a theory of probable cause.
Test the theory to determine the cause.
Establish a plan of action.
Implement the solution.
Verify full system functionality.
Document findings, actions, and outcomes.