stumped (?.)

• addled
• at a loss
• at a nonplus
• at a stand
• at a standstill
• at an impasse
• baffled
• bamboozled
• beat
• bewildered
• buffaloed
• confounded
• dazed
• floored
• fuddled
• in a dilemma
• in suspense
• licked
• muddled
• mystified
• nonplussed
• on tenterhooks
• perplexed
• puzzled
• stuck
• thrown