These are the three acceptable ways to end a sentence.
Only one of these is acceptable. (Can you guess which?) If you’re going to ask a question or exclaim something, only one of the corresponding marks is really necessary. Three might be, sometimes, maybe acceptable. Such as for a drunken text, or if you just won the lottery (!!!!!!!!!!!!!!!!!!!!!) Or if you’re referring to the band known as “!!!”
Mixing punctuation marks is a no, no matter what your situation. .! or !. is not acceptable. Are you exclaiming or stating? I’m confused. I think you’re confused, so maybe you should decide and then PICK ONE. Additionally, although it is feasible to both exclaim and state simultaneously (yet without double punctuation), asking a question and making a statement at once is a paradox. Therefore, these
?. / .?
MAKE NO SENSE! And these
ARE EQUALLY STUPID.
So do us all a favor and pick your punctuation like you pick a fine wine. Be decisive and selective, because right now, you only get one.