I have a 5yr old lawnmower, when I pull start it the engine never cranks. I've yet to change the oil or any spark plugs on it. I was wondering if anyone thought this would prevent the engine from cranking, or if there were other ideas. Despite the oil and plugs negligence, the mower is lightly used and has always been in the garage.

Change the plug, the oil, and clean the air filter. Prime and try again.

Does the engine sound like it has lost compression?

No surprise here.

No use changing the oil and sharpening the blade until it runs. While testing, you really don't need the air filter, but be careful about backfiring. Do make sure that there is enough oil.

So, that leaves the plug. Check for spark. Use spray carb cleaner in the plug to test for a sputter an we'll go from there.

YELL.

Check the oil before EACH daily use.

The plug and air cleaner should be replaced at least yearly. Oil changed at least yearly. Blade sharpened at least yearly.

Use high octane gas. Near the end of the season treat new fuel with Sta-bil. Run gas out of engine before storage.

If you don't want to do that then have someone cut your lawn or buy a new mower every year. Problem solved.