How long 120mg. well, the half-life of methadone can be up to 59-hours, so after 2 and half days you would still have 60mg's in your system. But this doesn't take into account multiple doses.
A third type of lock is a security lock. This lock is like a typical password, to prevent someone other than the owner from using the phone. If activated accidentally, the user manual or carrier customer service can usually tell you the default code.
The purpose of iPhone restrictions is to lock certain functions of the device. They are also referred to as Parental Controls, capable of hiding songs with explicit lyrics, preventing YouTube from running, etc. Without the four-digit passcode restrictions can't be changed. If you have forgotten your restrictions passcode you must restore your iPhone using iTunes to reset the passcode. When asked, do not restore the iPhone from backup, otherwise the old passcode you don't know will be enabled.