You can find a can of carburetor cleaner at an automotive store. It's poured into the gasoline and does a fair job of cleaning the carb. Unless you're astute at repairing small engines, just accessing the carb could be a chore, much less taking it apart to clean it. There's lots of small pieces and you're likely to have a few left over and that's not a good thing. Try the cleaner first and if doesn't work seek out a small engine repair shop.
For O.Geezer... any information applicable to the lawn mower engine will be useless for helping you with the "strimmer" assuming it's a two stroke engine (most are). If you mix the fuel and oil together it's a two stroke and the science is entirely different with the exception of still lots of small pieces, none of which should be left over.
One quick suggestion though... near where you set a control for cold starting or even a little plastic bulb pump primer will be two tiny screws fairly close to one another. One of these sets the idle speed mixture whereas the other one sets the high speed mixture. Using a very small bladed screw driver, turn both all the way in (CW), pull the starter cord through a few times (to clean the carb) and then open both about 2 1/2 turns (CCW). Try to start it... if it runs, adjust one of the screws to get a smooth idle and the open the throttle and adjust the other to get a smooth high speed.
Be especially sure that you have used the right oil/gas ratio... most are 50:1 (gas to oil) but be sure to use your owner's manual recommendation...