Application Pool Not Starting

We had issue in our environment where one of the application pool was not starting hosting all services. After looking at the logs and getting some sense of the error, we tried the following two ways:-

1) Go to App pool in IIS manager, Right click and open Advanced settings, Put in the new password or reset the password again. Once done, restart the app pool.
   If it doesnt start again, try the step 2

2) Go to the Local policy editor and under User rights assignment, add the app pool user under Log on as a batch job and Restart Group Policy Client Service (services.msc).