Towing Issues: my car was towed w/ no warning, heather, signs

Question
I dropped my car off for my boyfriend to use at work...I parked in the same place he does EVERYDAY where he has never had a problem they towed it anyways even though they are no posted signs ANYWHERE..what are the rules on this..they gave no warning or note or didnt ask who's it wasfirst? just took off and left it? Dont they have to have a sign atleast somewhere stating there is no parking w/ out permit or what so ever atleast somewhere? What can I do>?

Answer
Heather, I need more information on this question as to "WHERE IT HAPPENED" City and or State as the laws are different everywhere...

What the rules are in California are totally different than in Alaska verses New Jersey verses Chicago, or Topeka
Some states require signs and some do not require them to be posted...

If I have more information then I can help more.