1. compiz --replace
2. logout

When you can't access the minimise etc, try this

  with cursor in relevant window,   alt + space

that is, press      left Alt (usually next to space bar),    and     space-bar        at the same time

This brings up all the useful options in a drop-list, called the "op up window menu"

See  linux "Table_of_keyboard_shortcuts" in wikipedia etc

As dqjl111   says,  if the default is to show the frame and window menu , you can get a terminal:  ctrl+Alt+T (in the display you are using)
and invoke:
   compiz   --replace    &

The trailing single "&" lets compiz execute free of the terminal. If you do not this, compiz will be stopped when the terminal is closed. But it should auto-start again, in a little while.

Apparently it's to do with appmenu-gtk3 appmenu-gtk appmenu-qt

I hope all that helps.

H thanks for all the suggestions. However I have not had any problems with Deepin recently, so it seems to have fixed itself (probably through updates). Anyway it is useful to know and I will return here if any of the problems resurface.

Thanks again.