How to switch program in task manager while PC is turn

Question

Hi team,

I had project send message through whatsapp. Method is switch "WhatsApp" program is task manager, find Name that want to send and send. So far, The program is working good but when PC was running for a long time and PC was log off screen, the program can't switch  "WhatsApp" program to send message.

Anyone know how to solve it?

Thank you so much!