This article explains how new Linguist users can create their own password (when they log in for the first time and did not receive a password from their Project Managers) or how any user can reset their password in case they've forgotten it.
An example of a forgotten password and a link to reset it.
Just follow this "Forgot your password?" link and fill out your username (using your email address is possible as well, but can be tricky when you have more than one Memsource username connected to the same email address). The password recovery instructions will be sent to the email address connected to your username. Click on the link in the email, fill out your new password, and submit it.
Note that email clients (Outlook, Thunderbird, etc.) check the URL when accessing an email and this causes the link to expire. If using a client, open the link immediately after receiving the password recovery instructions.
Now you should be able to log in to your account.