Please help me.. How do I cash a large check of US dollars in nigeria? Please help me I reallly don't know..?

I was at the company hoping that i would be able to cash today, but to my greatest surprise, a cashiers check was waiting for me. I have been able to get the check and i have it with me right now but there is a problem down here right. The hotel manager has already seized my passport and other travel documents because of the hotel bills and he said he will not release it unless i pay his bills and now am in deep ****. I was hoping i would have used the cash to settle the hotel bills but didnt went as planned. I even had to report the case to the Nigerian Police here but they could not do anything about it, they told me that i have to find a way to pay the bills myself.