Its very common that in the project the initial Tridion installation was done long back and the current team members have no record whats the MTSUser credentials set at the installation time. Now there can be any situation, an issue to fix which needs MTSUser login to debug. Then the only option is to reset the password for MTUser but there are some road-blocks in this path:
As mentioned by Nuno in one of his comment in this post the below things can break:
1)Any COM+ related code (if you have any)
2)Search will stop working.
Is there any more possible issues that may come in picture. What should be the ideal approach to overcome the main Issue; How to get the MTSUser back again to ensure its working. any comments on same area most welcome.