2001 Honda Accord car wouldn't go in gear. For a bit

We left the car wash. Arrived at the stop light and waited for the red light to turn green.
As soon as it turned green I put it in first and started going then all of a sudden it seemed to slip out of gear.

the car was still running, so I put the clutch in and try to go into first. But it absolutely would *NOT* go into gear.I tried 2nd. Nothing.

i freaked out and asked my GF to steer while I pushed the car to the nearest parking lot. (Hard work for an overweight smoker)

anyway.I called my friend and he had me check the clutch fluid? And there was fluid in there. We waited and waited.

when the car was turned OFF, I could shift into any gear I wanted (first and reverse were kinda hard to get into). But when I started the car up.I could not get into gear.

i figured i'd put the car in gear (first) when the car was off. And put the clutch in and start the car. When I did that. It felt like the car wanted to go into gear (forward) even tho the clutch was all the way in.

anyway. My friend suggested putting the brake fluid in to the break fluid place and clutch place. Right next to eachother.

after awhile I was able to put the car in gear wihle it was running. Now everything seems to be fine.

if it was the fluid. Does it just go away and always need to be checked? I haevnt noticed any leaks anywhere recently.

thank you.
-G