Why doesn't my light stay on unless I wiggle the switch?
Recommendation - Replace the Switch
A light switch is a very simple, but also inexpensive, item. So (a) they shouldn't go bad very often, but (b) replacement is pretty simple.
It is actually quite possible that the problem is not the inside of the switch but rather one of the wires. The wires may be connected via screws (preferred) or through &quot;back-stab&quot; connections. Back-stabs are faster (by a few seconds) than screw terminals, but more prone to bad connections.
If it were me, I would buy a new matching switch - either regular or Decora - matching the existing style &amp; color of your current switch. Make sure it is a regular switch, not a 3-way switch, unless you actually have a 3-way switch (2 switches in different locations that control one set of lights).
SAFETY FIRST:
Turn off the breaker (you mention &quot;fuse&quot;, but on an 11 year old house you should have breakers). WARNING: If the box with the switch also has other switches (e.g., fan) or receptacles, there may be more than one live circuit in the box. So after turning off the circuit for the light, make sure than any other devices (e.g., fan, receptacles) that relate to that box also do not have power. In particular, you may have receptacles on a different circuit from the lights so that a GFCI breaker trip from a bad appliance won't turn out the lights. So make sure there is NO POWER going to the box when you have it open. The pros (and serious amateurs...) may not be as particular about that, but if you are new to this, better safe than sorry.
Remove the cover plate. Unscrew and remove the switch. If you have other switches or receptacles in the same junction box, don't mess with them! One thing at a time so you don't get your wires confused.
For an ordinary single switch, you should have 2 regular wires (hot &amp; switched hot) plus a ground wire. There is no functional difference on an ordinary (not dimmer, not timer, not &quot;smart&quot;) single switch between the hot &amp; switched hot connectors.
For a 3-way switch, you should have 3 regular wires (hot or switched hot, 2 travelers), plus a ground wire. In this case, it is absolutely critical that you wire things up correctly based on first figuring out which wires are the travelers and connecting to the appropriate screws based on the switch installation instructions. Screw positions may vary between brands/models of switches - e.g., travelers could be on the same side on one switch and on opposite sides (e.g., both top or both bottom) on another switch.
End result - if this is a single switch the whole process should only take a few minutes. If it is a 3-way switch, you may want to read up on that a bit first as it can be confusing.