There can be several reasons to why you are not getting any notifications to your email:
1. Wrong email address - it is possible that an incorrect or unused email address has been set as default.
2. You are not registered for updates in that particular forum - You can re-register for updates through the forum itself.
3. The updates have been transferred to a spam folder by your mail client - if this is the case, check the spam folder.
4. You mail client has blacklisted Moodle - In that case, contact your mail client operator to whitelist Moodle.
5. If is is none of the abovementioned scenarios, follow the steps below to perform a more thorough checkup:
Press on your name at the top right corner of the main page and select "Preferences".
Select the option "Notification preferences" which is under the header "User Account".
First make sure notifications are not globally disabled by checking if the checkbox at the start of the page is ticked.
Click on Email options to verify that there are no alternative email addresses to send notifications to.
In case there is, delete it and press save changes.
Scroll down to forum options and make sure all the notification options you want are turned on.