I sent a long text message yesterday and when it displayed in my messages it wasn’t all there

Was this an SMS or iMessage? If SMS, yes, with some carriers and some devices, very long SMS texts can get fubar’d. The SMS system is designed around single complete messages of no more that 160 characters. Carriers and devices have to break up long SMS and send them separately, then re-assemble them at the recipient’s end. That process is kludgy at best, and can often get messed up.

You‘re really far better off using email for long messages and not trying to rely on SMS instant messaging.

Bbrusco wrote:

iPhone 6s. 11.0.3 version Not sure is by the way nature message didn’t display and not sure if the recipient r ceived entire message

Try going to settings > general > keyboard and making sure that Smart Punctuation is turned OFF.