If you want to know whether your friend has blocked you on their WhatsApp account, below options can provide you more inforamtion

Who Blocked You On WhatsApp

Unable To Invite The contact To Join Any Group – You will not be able to invite someone to join any group owned (admin) by you . WatsApp will show / pop-up a error message if you try to do the same .

The Blue Check Marks Are Not Displayed – There are Three types of check marks on whats app.
1. Single check – Single check means user has not yet received your message on his phone or WhatsApp device . If user has blocked you , Or if user is not connected to internet or if user has deleted his / her WhatsApp account then only single check mark will be shown on WhatsApp message .
2. Double Check (GREY) – Double Check ( GREY) means that the user is connected to the internet connection and has received the message but not yet seen the same .
3. Double check (BLUE) – Double check (BLUE) means user has received the message and has seen/read the same .

No Profile Photo – No profile photo is shown if the user has blocked you . Also if the user has deleted the WhatsApp account or if user has removed the profile photo , then the profile photo will not be shown .
No status – No status will be shown for the user if he/she has blocked you or deleted the WhatsApp account or has removed the whats app status.

No Last Seen Are No longer Shown – Last seen will not be shown if user has changed Last seen preference setting in his/her privacy setting which is available in the setting tab . If the user has blocked you then you will not be able to see his/her last seen .