I cant see that image, and I'm guessing you use Xfce (though you dont
say so.) I hope I understand your problem, though I cant imagine how you
got to it.
Use Ctrl+ALT+F2 to get to console and log in.
You can manipulate Xfce using xfconf-query:
Something like this should work:
xfconf-query --channel 'xfce4-panel' --property 'panels/panel-1/size' --type int --set 32
Then ALT+F1 to get back (hopefully) to desktop.
Apologies if I misunderstand. If so, please give more details (not a
screenshot please)
unman