The way to stop a constant runny nose and sneezing depends on why you're nose is running and you're constantly sneezing.
If it's due to allergies then you need to get rid of the allergy trigger and use an air purifier in your home and also take allergy medicines and hopefully avoid the allergens if possible.
Then you can take allergy medicine and use a Neti Pot to clear your nose out of irritants.
If the constant runny nose and sneezing is due to the cold virus then you can take some cold medicine and medicine to help slow down the runny nose.
Also stay hydrated and clear your nose out using nasal sprays, net pot etc.
Use a humidifier in your home as well to add moisture to the air.
Taking a hot shower or even just sitting in the bathroom with the hot shower steaming is also good for runny noses.
Drinking hot tea, plenty of water and eating spicy foods can usually help with runny noses and sneezing as well.