How to revert Secure DNS servers?

Hi! Can anyone help me with how to restore my original DNS settings? Been having sporadic problems with internet connectivity since I installed Comodo and accepted their suggested DNS settings and would like to try changing back and see if that helps. Unfortunately Iā€™m a fairly basic PC user, so have no idea how to do this! Any help gratefully received!

Many thanks for your time, :smiley:
C

To answer your question:
Windows XP - Manually Enabling Or Disabling Comodo Secure DNS Service
Windows 7 / Vista - Manually Enabling Or Disabling Comodo Secure DNS Service