Can't access wifi from my mobile.

Hello,
I always accessed the wifi at my office on my samsung galazy s4., now i can't.

please note the following:

(1) the password for the wifi at the office has not changed.
(2) i cannot access any open wifi from my phone.
(3) i, however, can access wifi when i am home from the same phone.

is something wrong with my phone?

can you assist me here please?

thansk