My laptop wireless will turn off after long inactivity. There are two switches., One is a small hardware slide switch on the front edge. That is the Master switch. There is also a keyboard combo switch (Fn+F5) that brings up the On/Off menu. Both have to be on. It is the keyboard switch that needs to be reset after a long period of no usage.
Every brand probably has a different way of doing this. Mine is IBM/Lenovo (T60.) Check your User Manual.
There is a good reason for this - since the wireless function involves a radio transmiotter with antenna in the laptop lid, iut is a power user when on battery, and when in a public Wi-Fi area, if it is On, your machine is exposed to possible hackers. Ergo, the procedure to force the user to make a decision involving security and power.