alex
change of advice
you have a serial port
lets get a pci serial cardand the correct cable from amazon
i will help you configure
you will be in for $40 or less & serial ports never go bad
you might be in for $200 or higher if we opt to fix the board & there is always a slim chance of destroying the board.
it's your call. configuring will be kind of a pain in the ass (think root canal) but it will have a success at the end of your adventure
if you have alaptop order a good usb serialadapter. 
(sophie is having an ordeal with hers, but she will have a success at the end as well)
i did my first serial connection in the days when you booted your 
computer off a 5" floppy disk. no plug and play devices then.
so, if you order, i will work with you on this
		
 
Hello,NETSOL,  yes my GX-24  stopped  detecting my USB.  Verified cable not the issue.  I wouldn't like to take out the motherboard to verify solder points of the USB port unless I really have to. I do have experience soldering. 
***If the DIP switches are on the motherboard and need to be changed from Default (all OFF), then I  might as well do the soldering: 

 ***
I have "regular" 
computer knowledge. I have a Lenovo PC with only USB ports and 
Windows 10.
The below is from a 2020 Thead:
[My questions/comments in Brackets] 
usb to serial,convertors still need to be setup
go to rolanddga.com then support, them cutting.
find your device, download user manual
go to page 3 and print it[t
you have dip switches, check them. whole row on off is default
[What settting should the dip switches need, leave all OFF?]
whether you use usb serial or serial cable, all settings must match
[I bought serial-usb parallel  and a Null-serial female-female to plug on GX-24] 
on pc, go to device manager
open ports
choose your com port
choose properties
settings you want are either here or in advanced
[which settings do I look for?]
make sure all settings match what you found for the plotter
any changes made, power both devices down.
start plotter first.
wait a minute, then start 
computer, serial devices only try to link once, any change,
you need to restart
make sure settings are the same in your cutting program [sorry which settings? ]