(I apologize to everyone in advance for the length of this post.)
Thanks to everyone who is trying to help me with this.
The solution to getting texts on the "new" phone account is to replace the phone. I have bought a new, replacement
phone but have yet to go through some procedure where I register some sort of number on the new (replacement) phone with Virgin Mobile and then ask them to transfer my info from the defective phone to the new (replacement) phone. When that process is complete (and I have no idea how long it might take) I will have a fully functioning phone on the new phone line, and should be able to receive and retrieve any text messages.
With respect to the old phone number with the lost phone, I believe I lost it someplace in my house, so will continue to look for it. If I should give up hope of finding it, then I will have to ask Virgin Mobile which model phones are compatible with that account, buy one of these, and then have the info transferred to the replacement phone for this line.
I suppose I should tell you that each of these phones I have purchased so far has cost $15 or less, so it is a matter of inconvenience rather than significant monetary loss.
Perhaps I should also tell you that I have lost four items in the last year. I assume all of these were lost inside my house someplace. But I have begun to wonder whether I am going insane, what with losing all these things.
So far I have found two of them. One was my wristwatch. It appears that one of the pins that holds the wrist band to the crown of the watch broke, and the watch fell on the floor (without my noticing that it had dropped from my wrist), obscured by some papers. But it took me weeks to find. The second was my wallet. I was tired and lay down on my bed fully dressed (included having my wallet in my back pocket) and just fell into a deep sleep. When I woke up, I noticed that my wallet was no longer in my pocket. I thought that maybe it was too lumpy to sleep on, so I had removed it from my pocket when still half-asleep and put it on my mattress. This led me to think maybe it had fallen off my mattress onto the floor by my bed, but I looked there and could not find it. I spent several weeks trying to look for it, with no success. Last night I half woke up, and thought I'd read a little and then get back to sleep. I could not find my book, and somehow thought it might have slipped into the crack between the head of my mattress and my headboard.
I stuck my hand in there, felt something, and managed to pull it out. It wasn't my book; it was my wallet.
So perhaps I'll still find the old phone somewhere, sometime.
Thanks again for your responses. I think I know now what I must do.