1. The change you are trying is too difficult.
There are many different pull-ups, some of which may be easier for you than others. Their standard pull-ups start with shoulder-width hands and routine grip. Wide grip and tight grip pull-ups emphasize your latissimus dorsi upward, while reverse grip pull-ups require you to start with reverse grip. If you have fatal abdominal muscles, try Gorilla Gala, which requires you to put your knees on your chest when you are close to the barbell.
2. Your muscles are not strong enough
If you can't physically lift yourself off the ground, you may just need to start exercising the muscles of your back, chest and arms. Try your luck and do an odd pull-up. Grab a pole and jump up so that your chest can touch it. Hold here for 5 seconds, and then slowly lower your body for 5 seconds. Once you can correctly complete 10, you can do regular pull-ups.
If this pull-up is a challenge, start by exercising the muscles of the upper body. You need to do push-ups. Greatist provides some amazing changes, including lifting dumbbells, flat support, kettle bells and barbell exercises.
Your position is wrong.
Most people lift weights when they can't do pull-ups. The problem may be your serratus anterior muscle, which supports the scapula of the chest. When your SA doesn't work properly, the 17 muscle connected to your scapula doesn't work properly, which will prevent you from doing pull-ups. In order to adjust your SA, you need to start relaxing the muscles on your shoulders. When you sit in front of the computer or bend over to eat, you are turning your shoulders and moving your shoulder blades up.
Massage your body on the wall with lacrosse or tennis to counter this hunch. This will relieve the tension in your pectoral and teres muscles. Then according to the different movements of standard push-ups listed in men's magazines, start to exercise strength.
You must practice your mobility.
Sometimes you need to start with the basics. If you have difficulty lifting your chin to the barbell, it may be because you are not flexible enough. First, take time to do pull-ups and exercise your shoulders. Once you can hang it here in a controlled way, you can start to integrate the pull-up boom, which is an effective way to build shoulder stability and grip. These are two things you need to do before doing pull-ups.