The fact is that I have been very busy with an important job for the past few days, so I have not had sufficient time to read all of your message.
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Wonder123didn't have, or couldn't have or was unable toThese are past verb forms. They do not seem applicable to your sentence, which seems to call for present perfect.
Wonder123didn't had/couldn't hadNote that these are both wrong because you can have only the plain forms of verbs after forms of do or after modal verbs like can. have is the plain form. had is the past.