The reason could be a modified .bash_profile file.
Try putting these lines to ~/.bash_profile
source ~/.bashrc
Or a better way is to run the below command from your terminal
echo "source ~/.bashrc" >> ~/.bash_profile
To know more about how do we set environment-variables and what role do files like .bashrc, .bash_profile play, you may want to read:
- .profile or .bash_profile
- How to create ~/.bash_profile and ~/.profile
- I cannot find .bash_profile in ubuntu