If your truncate happened on Tuesday at 2:00 pm, get the backup file closest to, but earlier than Tuesday 2:00 pm, for example Monday night at 11:00 pm.

If your database is named "MyDatabase", then restore the Monday 11:00 pm Full backup with the name "MyDatabase_Monday11pm", which makes another database. Then copy the table data from "MyDatabase_Monday" to "MyDatabase". After the data has been recovered, you can delete "MyDatabase_Monday11pm".

Since your database is SIMPLE recovery, if data was added to the table after Monday 11:00 pm, you can not recover that. If you want to be able to recover all the data next time, then your database needs to be in FULL recovery, and then you also take transaction log backups every 30 minutes or so.