You should begin by testing the spark, as discussed previously. If the spark is satisfactory, the next step would be to inspect and clean the fuel filter. Instructions for that are on Page 79 of the workshop manual, which you can get here:

http://www.honda-engines-eu.com/en/images/992.pdf

If the filter and fuel line are clear, in view of the fact that the problem arose after you lent it to a neighbour (something I would never do, by the way - you now know why) check that there has not been interference with the governor mechanism, in particular the anti-oscillation spring.
[Linked Image]
The anti-oscillation spring is the small one at the top of the picture, slid over the outside of the wire link between the governor arm and the throttle butterfly. Also check the rest of the governor external mechanism, to make sure it looks just like the one in that diagram, with all of the parts connected just as shown. While you are at it, go through the simple process on Page 79 for adjusting the governor.


If all is in order with the fuel feed system and the governor, the next step would be to clean the carburetor's main jet and emulsifier, but I suggest you refrain from touching the carburetor until you've been through the process outlined above. Then if you post a progress report to this thread, we can talk about how to proceed from there. It seems to me that more Honda mowers get scrapped because someone has attacked the carburetor unnecessarily, than for any other reason.