computer A can see computer B, but not vice versa

have a desktop a laptop and a wireless router to which both are connected.
recently, i stopped being able to browse folders on the desktop when working on my laptop.
the strange thing is, is that the opposite is not the case - i can access the laptop from the desktop.
when i try pinging, the same happens: i can ping the laptop from the desktop, but i cannot ping the desktop from the laptop.
i don't even know what kind of problem this could be and the windows troubleshooter helped me not at all.
can anyone help?!

 

ok, ok. i sorted it out. another annoying firewall problem. have a good weekend, y'all