I created a passcode for my voice mail on the Mitel 5330e IP Phone, but now I have forgotten it and can't access my voicemail.

SOURCE: can't activate voice mail on Mitel 5212 IP phone

You need to verify your Call rerouting, you will also need to clear any call forwarding that might be active. Its possible the system is not able to transfer a call to the forwarded location.

SOURCE: voice mail password reset without current number mitel 5207 ip ph

What voicemail do you have? Login to admin mailbox or login to phone system if you have Embedded voicemail.

SOURCE: How do I remote access my voicemail and route

That depends on your Callmanager
Please rate my answer and Support me

SOURCE: employee left and we need

You will need to do this from within the Voicemail system. This is usually done by the site admin or your phone system vendor.

Good luck,
Mark

SOURCE: two lights on phone mitel 5212 ip phone

It sounds like your phone is in do-not-disturb. Press the blue key. Press the no (# key) until you see DND, then press Yes (* key). Press Turn off (0 key).