Default [Q] Not getting mount

Hi,
when i connect my nexus 4 to my pc it inst detected by my pc i connected it on a other pc it worked.
i tried installng uninstalling driver installed them manually too but it didnt worked!! im updated to 4.4.3
P.s when i connect it at camera i.e ptp then i am able to acces only two folder (DCIM and pictures)
help please!!