You mean those icon on the bottom right corner right. Right click blank space of where your icon used to be, select customize notification icon and play around with the settings to get your icons back. This will work unless you accidentally uninstalled or change program/service startup settings. In this case, reinstall and/or renable them. If you haven't touch the start up settings of those program/service (you intended it or not), then someone/something else is changing the startup settings of program/service. In that case, check firewall and virus.