You hear a sudden change in the relative wind. Both rudder pedals go to the floor. The yaw string is not straight.

This may not be right, but fair is fair and so I will stick out my neck. If it happened in the air, I would have to do something NOW without consulting any experts.

Explanation the adverse yaw:
A rudder cable breaks and my foot pressure pushes the pedals to the floor. The cable that I need to restore the rudder to neutral is broken. The rudder centering spring is not strong enough to neutralize the rudder and wind keeps the rudder "locked over".

Sub-scenarios:

2A The yaw string points to the right pedal (adverse yaw to the left)

There is an immediate danger of spinning and I have no rudder to recover from spin. Immediately drop the nose to avoid spin. Try right aileron to level wings. If that does not work, prepare to bailout. Let go of the stick, open the spoilers, and see whether the glider stabilizes itself. If glider enters spin or spiral dive, immediately bail out.

2B The yaw string points to the left pedal (adverse yaw to the right)

My lucky day! Glider has entered a turning slip and it is losing altitude fast. Drop nose to avoid stall. Level wings with right aileron to reduce rate of descent. Be very careful to not bank to the right.

Evaluate my ability to fly more or less straight and turn left without rudder control. Can I get where I need to be without turning right? (A right turn with full right rudder would dangerously skid and possibly spin.)

Consider the possibility of a "slip to land" LEFT hand pattern. It might be possible to fly in slight leftward turning arcs if it is not possible to fly absolutely straight.

Decide whether to attempt a landing or bail out.

If bailing out, consider where the glider might land on it's own and if possible keep it away from human settlements. If flying over a densely populated area, consider piloting and ditching the glider where it won't hurt anyone (except me the pilot)... possibly in a big lake? Or into the trees? Open spoilers and try to put the glider into a benign spiral.

If trying to land... fly a "slip to land" pattern. It might be better to land off-airport where there are less things to run into on the ground. If there is a crosswind, choose a runway where it is a left crosswind (since the left wing is dropped). I'm going to touchdown with adverse yaw and probably ground loop. If possible adjust pattern to avoid obstacles that might be hit by a ground loop. At touch down apply full airbrake, full wheel brake and full forward stick in order to push nose into ground and thereby minimize the energy of a highly probable ground loop. This is safer and it is easier to repair noses than wings and broken tail booms.