Was this your only launcher?
It makes sense that if you delete the only launcher you would loose your GUI. I was using ADW EX as my main one so I had no ill effects.
I suppose you will need to somehow get the twlauncher30.apk put back into system/app folder. And since you lost your GUI, you might have to flash back the stock rom.
I am not sure but maybe others can help you with more tricks.
Sorry to hear about your troubles though.
SG Note II - JB Stock
Captivate - AOSP JB
Touchpad - OaT LnT JB
Galaxy Player WiFi 5.0 INTL - Eryigit KPA GB Rom - Rls 3.5
Galaxy Player WiFi 5.0 INTL - CM10 Nightly
Galaxy Player WiFi 5.0 US - CM10 Nightly
Streak 7 - ICS -B4 CM9
Dinc 2 - GB Stock
AspireOne NetBook - Windows 7/Windows 8 Pre/Ubuntu/Android X86 (ICS)
Logitech GoogleTV - HC 3.2
Nexus 7 16GB - JB Rooted
Xperia Play R800X - GB