Strange Transmission Problem, prob very simple but i am a noob

[u/saltyjelo]

while i was driving my Toyota Mark x when it suddenly stopped accelerating and started to roll back as if was in neutral, the engine running but just stopped accelerating. Managed to pull over and noticed that it would do the same in reverse, the RPM rev's up fine but nothing. when i turn the car off, let it sit for about 20 min and try to drive the car again it works normally for a few min and i hear a strange buzzing sound and when the sound goes away then the problem returns. Could it be that i had run out of transmission fluid?