inner glass on door of my S502 come loose?

the glass on inner part of the oven door has come away from its surround, unscrewed panel per instructions for cleaning to see if I could fix it but just came off further. The rubber has come away from the door, oven is now unuseable can it be fixed or is new door required, we are pensioners so cheapest option would be great help. The item needing repair is an S 502 electric cooker made by Beko.