wireless usb stick help

Helo ! I need help i think thaht my usb wlan adapter has problems but i post here if someone have same problems and maby we can solow it ! Wlan usb 2.0 RXZ-WU61S it has worked 5 hours and then signal disapeard i tryed to reinstall the drivers but nothing helped i have my laptop 20 cm from AP but no signal . Adapter uses Ralink konfiguration utility and it cent find networks "no wireless network detected in range" i tryed to use zero config utility but same problem , I can se my AP yust for a second when i start my computer then it disaper. Thank you for your answers and sorry for my writing :-)!