It is unlikely that the adapter is suddenly "not properly installed", but Device Manager should show up any problems with it if, for example, its drivers have become corrupted. You could try running the Update Drivers option.
In the Network Connections folder, it should still appear as the "Wireless Network Connection".
It is always possible that you are getting interference which is causing your wireless network to lose connections. Frequent culprits are Cordless & mobile phones and microwave ovens, but other WiFi networks in the neighbourhood can also upset connections. Changing the channel number you operate on might help - the default is normally "11", try moving down to "7" or "4".