Please Help! How do I revert back to my custom ROM? [Asus Zenfone 5]

I yesterday Flashed Cynogenm Mod 12.1 on my Asus Zenfone 5. This was the first time I ever flashed ROM on a device. My device runs fine but both of my sims are not detected!. Also, root access is not enabled even when I changed the root access to apps and ADB from developer options. Whenever I open SuperSU it says "There is not SU binary installed, and SuperSU cannot install it. This is a problem! If you just upgraded to android 5.0 you need to manually re-root - consult the relevant forums for your devicce!" . I am in great trouble! please tell how can I switch back to my previous ROM or if the sim issue can be fixed. Please reply quick! Thanks!