Question: What is full and complete repentance?

Answer:  It is to cease that particular sin and turn towards Allah in regret for one’s actions 

Question:  What does tawbah literally mean?

Answer:  It means to turn back to Allah

Question: Is it enough to just say “God forgive me” after one sins? 

Answer:  It is a good start, but it must be followed with the cessation of that sin

Question:  Does Allah forgive all sins? 

Answer:  With repentance, He forgives all sins

Question:  Can people who are in hell be forgiven? 

Answer:  Yes, through true and sincere repentance