one of the mcb trips.have unplugged all items and will not reset

Then you have a fault. Contact an electrician.

One of the first things I always ask customers is "Have you had or done any work in the house, or bought any new equipment?" Putting boards in a loft can trap cables, a picture on the wall can go through a cable. The awkward question is: "Have you had or have any Vermin issues?" Mice and rats love chewing cables, and these need to be dealt with before repairs. If no to all of the above, MCB's / RCD's do break from time to time and cables joints can come loose, either way call a local, reliable and registered electrician.