How to recover windows data on an external hard drive formatted in time capsule

Hi there,

In desperate of some help.

I took a windows external hard which had data on it from a windows pc.

Plugged it into my Mac pro 13 and opened Time Machine. Time Machine then mentioned something along the lines of "erase - partion - cannot backup unless erase". It was not in that context but those words and phrases were mentioned. So without thinking i clicked erase.

What happened next was a newly formatted external hard for time machine back up appeared. It actually changed names from "untitled" to "Time Machine Back ups"

Apparently what i now need to do is:

Step 1) Format hard drive back to NTFS

Step 2) Recover the data that was on the hard drive.

What i tried to do is i downloaded software called StellarPhoenixMacDataRecovery and did an advance scan which took about 5 hours. The only info it recovered was what seemed to be system files from the new format. Approx 20mb in size. The data i lost was approx 100gb in size.

Please tell me there is a way to achieve step one and two without having a PHD in computer science and programming or parting ways with my hard earned cash?

Much appreciated