op used Coinomi wallet to make the exchange which doesn't require copy pasting any address so I don't think this would be the cause of the problem.
As I said, if OP used the in-built Changelly API then this won't be the cause of the problem, but it is still entirely possible that OP used his Coinomi wallet with the Changelly website or other interface which still required him to copy and paste an address.
Also I don't think orders do expire as the exchange rate will be calculated when the transaction get confirmed not when you send it (by default).
According to the Changelly blog, floating rate orders expire after 36 hours:
You will have 36 hours to send funds otherwise the transaction will be canceled automatically.
Fixed rate orders expire after 15 minutes. This seems to be in keeping with what Husires has said above. So it is most likely that OP's order simply timed out, and contacting Changelly support should resolve his issue.