This is what I remember. In this manga our main character is the most powerful person in the party of heroes. However, our MC is not handsome at all and he has I believe one of his arms missing and is very scarred from all the battles he has been through. Our MC is stabbed through the back with a knife by the other in the party because they fear he is too powerful as they were going to fight the Demon Lord in the demon tower that has been endangering humanity for all these years. Our MC falls to the basement and fights through it for years on end. He is finally able to clear all the demons and finally clear the demon tower. When he returns the amount of time that has passed is around several years to 20 years. But the biggest thing is that he is healed, his arm has grown back and he has become more handsome.
Was this in full colour or mostly black & white?– LogicDictatesJan 27 at 8:44
You are looking for The Return of the Disaster-Class Hero by Kakao and drawn by Redice Studio.
I was the greatest hero on Earth. "But he's dead. How could the guy we’ve killed come back?" "I dunno. But if he can come back, just let him." I really came back after 20 years? "Why're you so surprised? What? Did you do something to hurt your conscience?" You bastards. Just you wait.
In this manga our main character is the most powerful person in the party of heroes.
You are pretty spot on with what you remember. The group of heroes is made up of the 12 representatives of the zodiac signs + the MC
But the biggest thing is that he is healed, his arm has grown back and he has become more handsome.