It's always used in the plural, "Thanks to."

It may be used as a substitute for "due to," in which case the choice between "because of" and "due to" comes into play.  Some "authorities" make a big deal of this, and others say it doesn't matter.

I believe "Thanks to" would be considered a lower register usage than either of the other two.  That is, don't use it in formal situations (unless you're thanking someone for something).

There's also a sort of colloquial usage for "Thanks to" and "Because of" in which "due to" plays no part:

"I got a drunk-driving ticket last night, thanks to / because of you!"  "Thanks to / because of you and the divorce court, I'm now the owner of a new Cadillac."

In the negative, only the "thanks to" works.  It has kind of a sarcastic flavor.  "Well, I finally got my citizenship, no thanks to you!"  That is, you gave me no help, and you may have even hindered.

Re "due to" vs. "because of," "due to" may only be used in the following way:

"My absence was due to sickness," in which "due to" is the complement of a being verb, preceded by the subject.

Taking the bus was a big mistake , but was due to necessity.

I think you can use "because of" any way you like:

We left Wyoming because of the high cost of heating our home in the winter.

Some people will allow the substitution of "due to" in this sentence.   Perhaps someone has advice on substituting "thanks to."

Best wishes,  - A.