I can find what changed, but I need a few inputs first. With view access you can still get most of them.
What I need (required): 1. The change history rows. If you can open Change history in the Campaigns menu but can't download it, filter to the right dates and copy the table (date and time, user, campaign, change type, old and new value), or ask an account admin to export it. Change history goes back 2 years, so last month is covered. 2. Daily performance for the same span. Per day and per campaign: cost, clicks and conversions (and conversion value if you track it), from about 3 weeks before the drop until today. This is how I pin down the day results changed. 3. What dropped. Conversions, clicks, conversion value, or something else? "Results dropped" could mean any of these, and each points to different suspects. 4. Today's date. Needed to tell which changes are still within the 30 day window in which most changes can be undone.
Defaults I'll apply unless you tell me otherwise: - Drop date: found from the daily rows as the first day the metric fell, then confirmed with you. - Window: changes in the 14 days before the drop and on the drop day. - Since many people touch the account, I'll keep the user column as exported and won't attribute a change to anyone beyond what the row says.
Send these and I'll return the confirmed drop date, the changes in the window, before and after sums per campaign, the suspects ranked as hypotheses with a check for each, and the undo options. Nothing in the account changes without your approval.