need help! i have part of a blue window bar on the top of my screen in game. i play on full screen.

i dont know what buttons i pressed, but a combination of buttons lead to me having a fraction of a blue window bar at the top of my screen. i know i pressed the start button, and ctrl+alt+delete, and escape, i was trying to leave a game cuz i was lagging so bad i had to restart my client during that south-west isp lag the other day. anyways the lag was so bad it took like 15 minutes for me to rejoin the game (most of that time was a frozen screen of in-game trying to leave the game to begin with, so i was gettin pretty mad) needless to say i got leaver buster but thats not why im here. the main reason for this thread is PLEASE HELP ME GET RID OF THIS STUPID WINDOW BAR!!! ITS DISTRACTING AND ANNOYING AND I CANT FIND ANY OTHER THREADS WITH A SOLUTION! if u dont have a solution, dont say anything. im not here to chit chat or hear the community's stupid opinions and one-liner zingers, take that shit somewhere else. i need help!