ok let's start from the beginning.
i assume when you said you opened cydia and you saw a bunch of numbers on the top.... i assume they are in green and it says: SHSH: iOS and a bunch of numbers right?
If that is the case, open tiny umbrella (close skype because it uses the same port tiny umbrella uses... either way it will prompt you). From your ss, it tells me that you don't have the blobs on your computer... i think you need it to do the restore. Go to the advanced tab and check the box that says "request SHSH from Cydia" and also check the one that says "set host to cydia on exit".
after you check those 2 boxes, click the button above where it says "save SHSH".
after it is done, go to the general tab and it will show you some iOS versions... see which ones are the ones there... if you see 4.2.1 create the custom firmware of 4.2.1. Close tiny umbrella and launch it again (make sure you don't have itunes open). Then click the button that says "start tss server" and open itunes and dot the shift + restore and choose the custom firmware that you created.