Infinix Hot 12 Contacts Disappeared

I've been using the Infinix Hot 12, and all of a sudden, a significant number of my contacts have disappeared from my phonebook. I need a solution right away. Ever since I made the purchase, I haven't received a single software update, and accessing my contacts has become quite a challenge. It appears that a significant portion of my numbers are mysteriously absent, and I have thoroughly examined the settings without finding any apparent problems. In addition, I'm having occasional connectivity problems with my mobile, Wi-Fi, and Bluetooth connections.