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No resistors dont have polarity. To troubleshoot it, desold it from the PCB and check it. Can you please clarify what is your problem and why do you want to trouble shoot it?
Do you have an Ohm meter? You could measure the resistance by touching either end of the resistor and see if it is within bounds of what the color code says it should be.
google for resistance calculator and then calculate resistance using colour bands and compare that value with value of resistance on multimeter if its not matching then replace it.carefully solder the new resistor.resistor dont have polarities!!
Checking a resistor or many other parts while they are on a PC board is problematic. Yes, you can read the bands or other markings to see what value it is supposed to be and take a reading across it with an Ohm meter. The trouble is, if it is part of a circuit then you are measuring the resistance of the combination of all possible conduction paths through that circuit. Other components like transistors, diodes, coils, and whatever can create additional, parallel paths that will change/lower the readings you will get. Even though a resistor does not have a polarity and will read the same when measured out of circuit, no matter what order you connect the Ohm meter leads, other circuit components are not so simple so reversing the meter leads often gives very different readings if done "in circuit". When trying to check a resistor "in circuit" you will often get different readings if you reverse the leads due to the changing conductance of other parts.
In general, if you get a reading that is significantly higher than the marked value of the resistor, you can conclude that it is probably either open or changed to a higher value.
Only very rarely will you get a reading that is close to the marked value. Most often you will get a lower reading. You can not draw any definite conclusions from either of these, even if it reads as a dead short. For instance, a resistor that is in parallel with a coil will read shorted even though it is perfectly good.
Oh, another point. If you measure "in circuit", you can get very different readings if you change scales on an Ohm meter. Many Ohm meters apply different Voltages to the leads for different resistance ranges and a lower Voltage may not be enough to turn some semiconductor junctions ON while higher Voltages that are used for higher resistance ranges will. A junction that is conducting will show much lower resistance than one that is not.
Resistors very rarely go bad and most of the bad ones which I have found in circuits have either been black from overheat or just plain broken in half from mechanical damage. If the resistors in the circuit look OK, I would leave checking them for the last resort. I would suspect active semiconductors (ICs, transistors, diodes, etc.) first as they are the first components to blow from excess current. Next would electrolytic capacitors. Then coils. Then other types of capacitors and finally any resistors that do not show any signs of overheat or physical damage. Somewhere after active semiconductors, I would probably suspect the circuit board itself and the solder joints on it before checking things like other types of capacitors or resistors.
All of the above argues for NOT even trying to measure resistors "in circuit". If you do suspect a resistor, the best way to check it is by unsoldering one lead and lifting that lead from the board. Then check it with the Ohm meter. It should read correctly if one lead is disconnected. You do not need to lift both leads. Of course, chip resistors will need to be completely removed to check them.
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