some keys are not functinal on keyboard
 

I'm just installed slackware on my pc, and put it on the corner as a file server.
so I use ssh to get access to the linux box. Everything is working fine, apart from some keys are not functional in an editor, such as in vi, or vim, like the "delete" key, "backspace key", "up arrow" keys , etc. however it is producing working fin in the console.

any idea how to correct this problem, otherwise it is painful if I want to edit something in vi or vim

when you are logged in, check the term shell variable.
it is likely to be ascii or vt100. make sure your ssh/stelnet client is running the same emulation.
that may sort out the problem

can you tell me more in details, many thanks

when you are logged in to your file server, type
echo $TERM

that will show you the terminal that that session thinks is emulating.
if you want to set it to vt100 for your current session then you would type

TERM=vt100

if you use konsole on the client to access, go to settings - keyboard
and set it to the same value.
most client ssh/telnet programs, or shells which provide them will let you set up the terminal type.