unable to search

Hello,

My company used Adobe and we are currently experiencing an issue searching. We have a company that scans mail as a pdf batch and we have always been able to search these batches but recently lost this ability. I am not sure if we upgraded to a newer version. There is no longer a binocular search option on the left hand side. i have tried Ctrl + F and it does not work. I have gone to Edit, preferences, search and enabled fast find as well as purged cashe contents. If i open the document from a different place there is a binocular search option and it is searchable, i assume this is different versions? Sorry im not super tech savvy! Why would one be searchable but the other not?