Solution:changing directory delimits to white space.

while changing directory, cd command delimits to white spaces.

syntax:
cd directory_name

is the syntax for changing directory. cd command workout with directory without whitespace.

example:
cd Documents

this will workout. But if the directory name is 'pdf files' cd command

cd pdf files

will wont work out 'cd: pdf no such file or directory' will be the result if there is no 'pdf' directory this is because cd command takes 'pdf' as a directory, which delimits to white space. The cd command resolved by '\' before whitespace. The above example can resolved as,

cd pdf\ files

suppose the directory contains two whitespace i.e,'pdf  files', the command will be,

cd pdf\ \ files.

if your directory is 'pdf\files', then the command for changing directory is

cd pdf\\files.