If I am not, I will be

If I am not, I will be
 

Are my sentences correct in grammar?

-I am giving a presentation. If I was (or were) not, I would be doing something else.
-I am not going to tell you something. If I told you, something bad would happen.

If they are correct, can I change the sentences to 'If I am not, I will be doing something else' and 'If I tell you, something bad will happen'.

-I am giving a presentation. If I was (or were)were is much better here not, I would be doing something else.
-I am not going to tell you something. If I told you, something bad would happen.(of If I told you, it would come to nothing good).

Thank you~

Can I change the sentences to 'If I am not, I will be doing something else' and 'If I tell you, something bad will happen'?

The new sentences are valid sentences, but they have different meanings than the original sentences.

The new sentences predict what will happen in the future as a result of some event either in the present or in the future.

The original sentences state what would be true now (but is not true now) if some event happened in the past (but that event did not happen).

Thank you~