This thread is six months old and this method wouldn't have helped since they didn't have iFile installed.hello
i had the same problem and i fixed it
look Man, i downloaded Cydia app then i installed it really it is worked for me.
cydia app came back.
download (cydia_1.1.8_iPhoneos-arm) from below.
then copy it and paste in any directory into your iPhone via (ifunbox).
after that open iFile in your iPhone and touch the cydia app that already you downloaded and coch the installer tab, the cydia app will install, fainaly respreng or turn off or restart your iPhone.
the cydia app will came back. good luck.
i hope this help you.