normalize informal text

Hi everyone
I want to normalize my text but I do not know how?
Is the normalized operator doing this?
I want to identify the words that the user has written briefly and write in full. For example
img -> image
Or replace the abbreviations with the original. Like
DM -> dimention reduction
  Or I can correct words that are spelling mistakes. Like
gud -> good
Please guide
I'm waiting for the answer.
Thankful