Hi,
Below will be some comments on regards of your questions/issues:
Q1 >> Unable to detect the USB port
[NXP]: Which Debug Probe are you using? If it is S32 Debug Probe, can you see it under the "Device Manager" as follows (or similar):

If so, was the S32 Debug Probe already connected when you enter the specific window? If not, you need to click the refresh button for the GUI to scan for newly connected devices.
Q2 >> Also pls help me with the FSL image,Pls share the link for the download. Is FSL is required to detect the serial boot mode?
[NXP]: Can you help us elaborate more on regards of what "FSL image" means?
Q3 >> unable to complete the demo code blinking LED.getting the below error.
[NXP]: Which demo are you following? Can you help us elaborate on the different steps you have followed? Which RTD version are you using?
Please, let us know.