What is the difference between Hast du mich gefragt? and Fragtest du mich? ?Feel free to just provide example sentences.

Not much.
The first past tense form is what Germans refer to as "perfect":
auxiliary verb: HABEN or SEIN; past perfect verb form: ge + verb stem + T/EN ending
fragen ( ask ) hat gefragt
gehen ( go ) ist gegangen
kommen ( come ) ist gekommen
It is generally used in colloquial speech and personal letters/mails/posts.

The second is called "Präteritum":
verb stem + TE
Generally it's used in written language, such as official letters/documents, newspapers...etc

Their meaning is entirely the same! However when to use which can be tricky at times because German people don't hold themselves to their rules much.

Usually when Modalverben ( können - can, dürfen - be allowed to, wollen - want, sollen - should, müssen - must, möchten - would ) are used in a sentence Germans use the Präteritum past tense form:
I couldn't see anything.
>>> correct <<< Ich konnte nichts sehen.
>>> odd <<< Ich habe nichts sehen gekonnt.
I had to wake up early.
>>> correct <<< Ich musste früh aufstehen.
>>> odd <<< Ich habe früh aufstehen gemusst.

Regarding your sentences, both are used in daily conversation but "Hast du mich gefragt?" sounds more...how should I say...a tiny bit more natural than "Fragtest du mich?" but it really depends on the person which is used more often.

By the way, be careful where you put emphasis. If you raise your intonation at the end of the first sentence it means you didn't quite catch whether or not the person asked you something. In contrast, if you put a little emphasis on "mich" you wonder if the person aimed their question at you. "Fragtest du mich?" in this sense is more direct because it puts emphasis on "mich" by having it stand at the end so it literally means "Did you ask ME?".