I wouldn't panic yet.
Assuming you are shooting bench-rest (the only
way to go, other than prone at this point):
How many shots did you fire between each time you walked out to change the target? Each time you should tape the holes or put one of those adhesive (or the kind you lick) dots on the holes, other wise it's easy to lose track of your progress. Also a spotting scope is a big help.
Maybe you're already doing this stuff. Then try this:
Remove magazine,the bolt carrier, and check that the chamber is empty.
Rest the gun on sandbags.
Look breech-to-muzzle through the bore and align with the black on a 100 yd target.
Next check sight picture without disturbing gun.
If the sight picture is to the left, adjust the rear sight to move the aperture to the left. If the picture is high, either lower the front sight or raise the rear sight, depending on what kind you have. You can estimate the amount of adjustment needed by moving your head and paying attention to how far
the sight is off by.
This adjustment is opposite in direction to what you would use when shooting, because while shooting, the sight is aligned to the target and the bore is not aligned. In this preliminary stage, the barrel is aligned and you have to bring the sight into alignment.
When you get to the point where you have a right-on sight picture while the bore is centered on the black, stop this part and safely get ready to fire.
At this point I think you should be able to get on the paper consistently.
It helps to have a friend or fellow shooter watching the target area with a spotting scope, telescope, or at least binoculars.
You want them to watch whether you're off the paper to the left, right, high, or low. If they don't see impact in the dirt or whatever, then they look to see if you hit the target and if so, where. I find it hard to see the holes with binoculars.
Use the clock face and the scoring rings for reference. They can mark numbers for each shot on a circle drawn on a piece of paper, and give you verbal feedback on where the bullets are going. Hold on the target exactly the same (no "Kentucky windage) each time and shoot three to five rounds.
Assuming you're on the paper, judge from the group's 'center' what kind of adjustment is needed. If you miss paper consistently, your helper should be able to tell you where they're going.
Now make sight adjustments as needed. Personally I only change one - either windage or elevation - at a time.
Cover your target holes and start again, or if you're keeping good records and have good optics.
If you are not getting consistent groups, see if somemone else has any better luck. However, their sight picture may very, so it doesn't make much sense to be swapping back & forth. One or the other of you should do the sighting in adjustments.
If nobody gets consistent groups in calm or steady minor wind, I'd start looking at the gun.