Unable to Connect to WIFI USB ADAPTER(Realtek 8188eu)

I am having "Realtek rt8188eu" WIFI usb Adapter. Ubuntu detects my wifi
connections but the problem is it fails to connect. It doesn’t connects at
all..and also its signal strength is very weak...I Had tried every solution
but no success please solve this issue. I had also tried the latest mainline
kernel 4.3 but it doesn't solve my issue. It always shows connecting status
in network manager but never connected at all. I am unable to use my Internet connection and I had also tried the driver from github but same problem. Please help.

Thank-You