1.
If you ~ or if someone turns you back when you are going somewhere, you change direction and go towards where you started from.
She turned back towards the crossroads...
They were very nearly forced to ~...
Police attempted to ~ protesters marching towards the offices of President Ershad.
PHRASAL VERB: V P prep/adv, V P, V P n (not pron), also V n P
2.
If you cannot ~, you cannot change your plans and decide not to do something, because the action you have already taken makes it impossible.
The administration has now endorsed the bill and can’t ~.
PHRASAL VERB: with brd-neg, V P