2010 galant speedometer, turn signals, check engine light on after vehicle sat for 3 months

Just have to tear into it, get the vehicle scanned for trouble codes, that would tell you why the check engine light is on, the turn signals I would try just moving the bulbs around in the socket, may have lost contact, the speedometer, there is a speed sensor on the trany that may need to be changed. Since it is a sensor, it may show up on the scan.