whenever i do
dfx start
Command ‘dfx’ not found, did you mean:
command ‘df’ from deb coreutils (8.32-4.1ubuntu1)
command ‘dfc’ from deb dfc (3.1.1-1)
command ‘dex’ from deb dex (0.9.0-1)
command ‘dx’ from deb dx (1:4.4.4-15)
Try: sudo apt install
I have installed latest dfx version still facing this issue 
The install script prompts you at some point to add something to PATH. Can you try running the install script again and making sure you follow the instructions about PATH?