Five alternative words which you can use instead of 'Sorry'

Made mistake and don't feel that the word 'Sorry' is enough to apologize, then here are some alternative words for Sorry, which you can use instead of Sorry. 

1. I take full responsibility
I take full responsibility is an alternative phrase for sorry, and it means that you know your mistake and takes full responsibility for it. 
Example:  I take full responsibility for my actions that went wrong. 

2. Regretful
Regretful is the word that shows that you feel sorry about something. 
Example: I am so regretful for what I said, I assure you it won't happen again. 

3. I should not have
I should not have is used to express that you regret committing a mistake and know that you should have done something else instead.
Example:  I should not have driven during the storm.

4.  Oops!
Oops is used to show recognition of a mistake or minor accident, often as part of an apology.
Example: Oops, I dropped your clothes. 

5.  Excuse me
Excuse me, used as a polite apology in various contexts, such as when attempting to get someone's attention, asking someone to move so that one may pass, or interrupting a speaker.
Example: Excuse me to sound off, you're not right.