Hello all and Happy New Year to you

My house is 3 years old. I have recess lights in my basement on a 2 way switch (one lightswitch on one side of the room, another on the other side). A couple of months ago I went to turn the light off by the lightswitch and it won't go off. So I walked to the other side of the room and used that switch and they went out. It's just been that way and we know not to use the other switch until we found out what was wrong. However, now the lightswitch that we use is a double switchlight (one switch controls the basement light, the other controls the lights to the staircase. Now lately the staircase lights are doing the same thing. I have to walk back down the steps inorder to turn off the light. (Annoying). Finally the other day I find that the lights in my kitchen are now doing the same thing. I have to walk across the kitchen to turn off the light because the other lightswitch won't turn if off when I flip it. These are all recess lights by the way. What is going on? And how much do you think it would cost me for an electrician to look at it. Thanks for your help.