How to find who was developer of my townhouse

Call your local appraisal district, or District Clerks office. You can find them in the phone book, usually under the County Government listings.
The county I live in posts some public information information online, so you might can find it there
Also you could call the clerks office and see when the original Deed to the house was signed, and that should probably show at least the builders name, which is often the developer as well
If not, maybe it will at least start you on the right track

Good luck

Very Simple. Contact a Realtor they have access to MLS which is a Multiple Listing Data Base which shows them the year the property was built and builder. Realtors, also have access to Title Company Representatives whom hold the information that you're requeting as well. Good Luck!