why my iphone 5C bought is not working now with verizzon sim?

You can't use that phone with Verizon. Verizon is a CDMA carrier. If you want to use Verizon, you need to buy a Verizon phone.

(there are ways to get an unlocked phone to partially work on Verizon's LTE network, however, Verizon does not support it)

Marguita wrote:

I bought in T-Mobile store for a prepaid sim an Iphone 5C and now I have a contract with verizzon and the SIM is not workin

Trade in your phone to Verizon. You'll probably get enough to buy a 5C that works on Verizon. And, it will be an unlocked phone.

In theory, if you put a Verizon LTE SIM in an unlocked phone, the phone should work on Verizon's LTE network, though not on it's 3G network You may also not be able to access all features. However, in practice, phones from other carriers don't seem to activate.