Did you have it unplugged from the last time you used it? Did you plug it back in AFTER starting LFS or before? Just close LFS, unplug and plug back in, then start LFS. You can't plug the wheel in after LFS is running. I've had this happen to me as well on occasion even with having the wheel plugged in first (I rarely unplug it). I just close and reopen LFS and it is working again.
Logitech wheels are constantly calibrating. Once you start LFS, or if you just plugged the wheel, steer fully lock to lock to calibrate and you should be ok. There is also a setting at the bottom of the options -> controller screen when you have the steering/pedal axis selected. You will see recalibrate, calibration lock, and remove deadzone at the bottom. Just make sure calibration lock is set to no, then you just do the lock to lock rotation when you first start LFS and it's calibrated. Also make sure you have remove deadzones checked yes.
There is no "calibration" button in the software. If you are talking about the profiler, then that is not the right place. Go to your control panel -> gaming options and you will see a graphic of the wheel and brake / throttle pedals. Just move your wheel lock to lock and push the pedals fully to calibrate. There's no button to press. One thing I notice is my calibration is different when I switch from another sim to LFS and back. I also race NR2003 and Racer, and I usually have to calibrate the wheel when switching between them all.
Hope that helps.
.