Was there battery voltage both sides of the fuse holder with the fuse in place ?
Prime suspects on a first mow of the season is mice nesting in the mower over winter and having a midnight snack on your wires .
Second suspect is corrosion particulalry of the ground cable .
Next is a battery that has now amps but they usually at least click
Start by pulling the engine cover off and have a bo-peep
After that jump from the hot side of the solenoid to the trigger wire on the base
Engine should crank is battery & cables are OK
Also load test the battery. As in a must do, place it under a proper load. Get it done free an your local auto parts store.
As Bert said, check your grounds.
Everyone, for some reason, ALWAYS checks the positive side of the circuits. Then totally ignores the grounds. Unless you have one of those new batteries with a single terminal on it. LOL