RE: Dell Inspirion 3148 keyboard (left side keys like 1, Q, A, Z, Caps Lock) keys are not functioning)
I'm assuming you have windows 10 on the system.....
I'd suggest you check Sticky keys in control panel. You might have mistakenly turn it on.
At the left bottom of taskbar, right click windows icon, click on Control Panel, Ease Of Access, and then Change How Your Keyboard Works. If there's a check mark in box - Turn on Sticky keys) then uncheck it and click Apply.