Changed Tranny Fluid and Now Wont Shift

I understand that the transmission fluid needs to be changed every 30K miles or so, however I bought this car last year and it sat through winter. I've put as little as 6K miles on it and just recently changed the Transmission Fluid in it (yesterday), when I woke up this morning to drive to school, my transmission would not upshift at all unless I over revved the engine by quite a bit. Im wondering as to whether or not my transmission is save able or not. Any input is greatly appreciated

Welcome to AF, always post the year and engine. You may have knocked off the vacuum hose on the modulator, check and post back.

Check the Transmission oil with the engine hot and running!