Dell Latitude 5420 laptop, the charging indicator light does not light up when the laptop is off.

Is this a Latitude 5420 (2021 model) or an E5420 (2011 model)?

@ejn63​ Brother, Its Latitude 5420. 

The Latitude 5420 charges over USB-C Thunderbolt -- it doesn't have a separate charging port (the E5420 does).

If the system is a 5420 and does charge over a USB-C cable but not with the OEM adapter, the adapter is suspect.

If the system is an E5420 and charges over USB-C/Thunderbolt but not with the barrel connector, it's either the adapter, the barrel port or the mainboard that's faulty.

@ejn63​

Brother, mine is Latitude 5420, not E series. And it also has the option of USB Type-C charging port. However, I could not understand whether it is an OEM adapter or not. I mean whether it is original or not. However, the charging indicator of the laptop used to work properly before. I have been suffering from this problem for quite a long time. Due to which, now I have to charge the laptop by turning it on.

I also thought that maybe it is not getting power properly, so I checked by plugging the charger into all the plugs in the house. Same situation.

If you could tell me the main thing to do in this case, I would have benefited.

Both USB-C/Thunderbolt ports on the left side will charge the system.  They are identical in functionality. 

If one works and the other doesn't, the port that doesn't work (or doesn't work reliably) is likely not making good contact either with the plug or the mainboard.  If the other does work, just continue using it.

The only sure repair for a bad or marginal USB-C/Thunderbolt port is either to have it replaced (requires soldering and likely a cost of at least $100-200) or to replace the system board at similar cost.

@ejn63​ Brother I understand.
This is really disappointing for me :( 
It occurs only when the laptop is off. But, when the laptop is on, if I connect the charger to the charging port, the indicator lights up immediately. 
Also, everything works properly with this Type-C pen drive. The only main problem is that when the laptop is off, I can't see the charger when I connect it to the charging port, because the indicator doesn't light up.

@ejn63​ I forgot to mention one important thing, sorry.
That is, if I connect the phone's Type-C charger to the USB Type-C charging port while the laptop is off, the charging indicator lights up.

I just did this to test if there is any issue with my laptop's charger.

@ejn63​ Ok Brother, I will try a new OEM Dell AC Adapter and I hope the problem will be solved.

@ejn63​ Now, after changing my AC Adapter, everything is normal.