Is there a way that I can read my texts and listen to my voicemails from Sprint online?

My iPhone is broken and won't turn on. However, I need to read some texts and listen to my voicemails to answer to something quickly. I won't be getting a new phone until next week and this is urgent.

Call your number to listen to voice mail.
Press either # or # during the greeting. Follow the prompts. Complete instructions are available on sprint's website.

For text messages… If you use a Mac, then the iMessage application will show the messages (whether sent from another iPhone as iMessage or any other phone as text). Same if you use an iPad.

If you don't use MacOS or iOS devices (other than your iPhone), then I don't think you can get to iMessages.

Log into your iCloud account, and if you had it active, your text should be there to read and reply to. Your voicemail will be on your cell phone provider's voicemail server, unless you deleted them.