My landlord ( I live in a Mobile Home Park) had a constable close up my trailer because of failure to pay rent. The landlord told me later that day that if I paid what was owed I could get back in. I paid it and now they won't let us back in. Can they do that?

Sorry if I sound naïve, but "constable"? I know the term, I just don't recall having heard it apply in the US. Is this in the states or another country?

In the US, it is not legal to bar you from the house unless you have already been legally evicted by a court and your properly has been removed by the sherriff.