You may have sucked up weeds or something into the intake grate and/or impeller. Make sure that is completely clear first. Sometimes it's hard to tell if it's clear until its out of the water.
If your sure it's clear and the ski is not out of the water, get it out and put it on the trailer and make sure it is clear again from the underside and back with a flashlight. If so, start it and from the rear, see if the impeller is turning while it is running. If not, work back from there to the driveshaft, take off the grey plastic pto cover at the rear of the motor to see the driveshaft.
The jet pump system is a very simple system, most people with just basic mechanical knowledge and tools can remove it and diagnose problems easily. People here will help.