NEED HELP 05 trailblazer tranny no noise or nothing

[Tbluvr]

05 tb tranny started slipping bad. Parked it 5 mos went out started it up and I have all gears again?? Unheard of what should I do?

 

[Mooseman]

Drop the pan, check for bits of metal or other abnormality, replace the fluid and filter.

 

[KEEBZ489]

how many miles ? while you have the pan dropped ( messy as hell ) it would be a good time to put in new shift solenoids. I just did a fluid changed myself , they are pretty easy , just need a small hook or large paper clip with the very tip bent over to grab the retainer spring. only about $10 each. had I know the potential mess I would have sprang an extra $35 for a pan with a drain plug for future fluid changes between filter changes