Tenda Support

i have a tenda w548d. seems like the ssid is visible an able to be detected by my laptop. all this whil i do not have any problems and the connections was great. lately i couldnt get to connect to the w548d eventhough the ssid is visible. why is this?

The router was connecting three computers, but suddenly disconnected. The light on the router is flashing in a strange way until now, the flashing order is: 1 only, 2 only, 3&SYS only, all except SYS, and toe power light is always on. What does it mean? Anything I do with it?