What are the next steps after a failed bladder sling surgery?

Further evaluation. Recommend seeing a urogynecologist or a urologist with female reconstructive surgery expertise. You should have a urine test and voiding diary to rule out non-surgical issues. Then cystoscopy and urodynamic testing for further evaluation. Depending on what type of procedure you had in the past, you may or may not be a candidate for a revision +/- new anti-incontinence procedure.
Urology consult. A urologist will be able determine what the specific problem is, which will determine the necessary treatment.