to say I did not...is it, mwen pa te fe or pat fe?

Both are correct.
One sentence is uncontracted: (Mwen pa te fè)
And the other is contracted: (Mwen pa t fè)

One little note*
Do you mean "I did not do."  or  "I did not do it"?

I did not do.
Mwen pa te fè. (uncontracted)
Mwen pa t fè. (contracted)

I did not do it.
Mwen pa te fè li. (uncontracted)
Mwen pat fè li. (contracted)


When "I did not" is used as an auxillary, it doesn't translate in Creole.

Examples:
I did not undestand.
Mwen pa te konprann. (uncontracted)
Mwen pa t konprann. (contracted)

I did not go.
Mwen pa te ale. (uncontracted)
Mwen pa t ale. (contracted)

I did not sleep at all last night.

Mwen pa te dòmi menm yè swa. (uncontracted)

Mwen pa't dòmi men yèswa. (contracted)

Ask me anything