You don’t have to do anything, as it says your ticket and reservations remain valid. You’ll just arrive a bit later than initially planned, and have to go to the station earlier. Probably due to some engineering works. No need to worry.

Due to works trains run at different times in August (there are also less services).

Your booked RJX 860 instead runs as RJ 860 leaving Vienna Airport at 09:35 and making more stops along the way (same arrival time at 12:53).

Either take that one or a later connection (likely with change at Wien Hbf -> Vienna main station).

But i can’t find my train in alternative options am i only limited to the below options that starts at 10:02 as my original train

or may i choose this earlier which is the same as my original route

9:35 is very convenient for me, so do i board the train with my original ticket that says 10:02 or do i have to change the tickets ? and if i need to change them how do i change them ?

As @thibcabe said , your initally planned train ís the one at 9u35, that now leaves 30 min earlier than 10:02 because of works. You need to arrive to the station earlier, but your reservation will still be valid.

Thanks a lot for your help, I forgot to mention that my tickets are a Sparschiene ticket does this change anything,or do i get to board 9:35 train with my current reservation?

Doesn’t matter which ticket or reservation you have. All tickets remain valid on the train that is now a half hour earlier.

Thanks a million for your clarification