Hello I'm struggling with the use of apostrophes and the ending s versus ies.

The bodies ability to repair and regenerate

Would this be bodies, bodys, body's, bodies' or bodys'?

I don't understand. I know when to use them is there is a missing letter, i.e do not=don't etc...but can't grasp the above.

Hi Willingtolearn

Body's is the possessive form when you refer to one body (singular).
Bodies' is the possessive form when you refer to more than one body (plural).

If your phrase refers to the 'human body' in general (and is therefore singular), for example, it would be correct to write it this way:
''The body's ability to repair and regenerate''

Proper noun Jerry.

Would you say we have more Jerry's, Jerrys', or Jerries?