The six most common reasons that an LG dryer will not start are a blown thermal fuse, faulty door switch, a bad drive belt, broken drive motor or incoming power supply problem. A failing main control board can also be to blame.
A blown fuse is the most common cause of an LG dryer failing to start, so check that first. The next troubleshooting step is to check the door switch for an audible click when opened or closed if no click is heard, use an ohm meter to check for continuity. If the drive motor can be heard running, then the belt is probably slipping or broken. The drive motor, incoming power issues or a main control board problem are less common and may require a technician to fix, so always check the other items first.