Perhaps something like 'you seem upset, I'm here if you want to talk'.

Then... If you are pretty sure that they are upset, but they don't want to talk about what is bothering them... Then perhaps you can help them feel better some other way. Maybe you can do something kind for them to help distract them from their hurt. Maybe you can go for icecream with them. Or maybe you can try and distract them with something else that you know they like or enjoy.

It can help to know that another person notices our upset and... Wills it to be better. Feels smoethign of our pain too just because they are human and emotions are a bit catchy like that.

Don't know if any of this will make any kind of sense to you..