I've had it for three years. Went out today to mow for first time this year, and it won't even crank. New battery? New sparkplug? And where can I get these?

Chances are it's the battery.have you tried to jump start it ?

No, I haven't. I'm not very tool-savvy, especially with something this big (for me). Should I just try to charge the battery? Should I just replace it?

Charging may work. However,what I would do is remove the battery and bring it to an auto parts store,and have it tested,to see if its still good. Then if it is you can charge it or they may charge it for you, or if not purchase a new one while there. That way there's no guessing about the battery,and you should have trouble free starts . Good luck.

Chances are, the battery is bad, discharged or has no water.

If the battery has caps, open them and check the level of the water. For less than $5.00 you can purchase a hygometer. Looks like a turkey baster with a needle.

What's more important than the actual number (specific gravity) is the unifomity.

You can have the battery tested at an auto parts store and possibly a lawn mower repair shop.

It is important to trickle charge the battery when in storage.

There also may be safety switches preventing the mower to start.

In this case, the tools needed are a hygrometer, a voltmeter and jumper cables.

Hygrometer - test state of charge

Voltmeter - determines if it's a battery of other electrical problem

Jumper cables - can get you going - jumping from the car battery.

Any small engine needs a seasonal tune-up which at a minimum consists of" air filter (inspect/replace), spark plug (gap and replace), oil change, blade (shapen and balance) and a generl clean,lube and inspect. It may have to be done more often.