Hi Koorosh Hajiani,
Which MCU are you using? I would recommend you to use the LPCOpen examples as reference:
LPCOpen Software for LPC11XX|NXP
For example the package for the LPCXpresso LPC1125 board comes with various examples to help you get stated, there you can find the corresponding *.ld and startup files:

Please notice that the linker script is autogenerated into the Debug/Release subdirectory of your project, in case you want to tweak this template for project specific requirements you have to place a local copy into your application project, take a look at this post that explains how to do it:
Linker script templates
Hope it helps!
Best Regards,
Carlos Mendoza
Technical Support Engineer