I have the L6405E error and I don't know how to solve (lpc1788) please help me
Interesting - now you posted new information. Information that still doesn't represent full error messages from compiler or linker. Is it a policy of yours, no never post complete information? Or is it that you, yourself, never want to read the complete information just to "save time"?
If the compiler sees that you try to call functions that it doesn't know about, then it's reasonable for the compiler to complain. And it's then reasonable for you to spend time trying to figure out why the compiler doesn't know about these symbols. Have you forgot a header file? Have you included the wrong header file? Have you forgotten to set a #define?
Maybe you should break the bank, and for once write a post where you tell us exactly what own work you have done to try to understand these error messages - and what own work you have then done to try to solve them.
Google can give good explanations for most build errors - if you just specify the correct part of the error messages when searching.