I used to have an iPhone & iPad & could receive iMessages to both. Now i have a new phone (not an iPhone) but i am still getting message from people with iPhones to my iPad & nothing to my new phone.
You can't get iMessage on android phones (which is, I presume, what you've now got). You would need to use what's app or something similar, or just use Facebook messenger. Beware scam apps which claim to provide an iMessage service for android.