Lightroom 5.7.1 not leting me into my last working catalog

My Lightroom has stopped letting me entering my last worked catalog.Worked fine one evening,but not the next morning.It seemed to have played up since a recent windows 10 update.
I get a window of info of the catalog saying Lightroom can not be use catalog named..... because it is not wrightable and cannot be opened.It tells me to select another catalog,but I am not able to find the files that I was working on.
Any idea's please.