Springtomize does actually work fine- not to start a flame war here, but it does. The poster above has been quite vocal about it, negatively, but I and many others have had no real troubles with it. When I locked myself out, I had a tap to unlock theme and by setting Springtomize in a certain way, I over-rode my slide (tap) and couldn't get in.
SHSH is a way to get into your phone/pad through Wifi. It needs to be installed through Cydia, as does SBSettings. If you haven't installed them, you will not be able to use them. There are apps that you can use via cable that will let you in to your device to remove Springtomize or anything else, as well as to download things to your device. I believe one of them is listed above. There are others as well. Google may help. Or you could make it easy and simply do a restore and then install your backup, making sure, this time, to install SBSettings as soon as you jailbreak. SafeMode is your friend.