some times wireless network adapter not works

[mk260712]

Problem :
from last one month my laptop wifi is not working sometimes.sometimes my system is not loading wireless network adapter.im unable to find it in Device manager and there is no any yellow marks or other devices.when wireless network adapter is loaded well it appearing in device mangaer and wifi working smoothly even for hours but after restart it eitherthe wifi is not work(no network adapter in device manger) or work well.
what i did :
i installed os freshly three time but no use
i reinstalled wlan drivers many times but no use

Info :
laptop : fujitsu lh 531
Os ; windows 7 Ulitamate 64 bit
Drivers : fujitsu official site drivers

please help me.thank you

 

[mk260712]

there is no any other symbols(even like other devicers etc..) and the router is working well with other laptops.

 

[mk260712]

Check what is the symbol we can see in front of the "Wireless adapter" in "DEVICE MANAGER. check whether it is ? or !. If you see this symbols it is the issue with wireless adapter.

Else it might be an issue with the router.

 

[mk260712]

there is no any other symbols(even like other devicers etc..) and the router is working well with other laptops.